Digest ZSTD compression dictionary once when writing SST file (#4849)

Summary:
This is essentially a re-submission of #4251 with a few improvements:

- Split `CompressionDict` into two separate classes: `CompressionDict` and `UncompressionDict`
- Eliminated `Init` functions. Instead do all initialization work in constructors.
- Added test case for parallel DB open, which is the scenario where #4251 failed under TSAN.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4849

Differential Revision: D13606039

Pulled By: ajkr

fbshipit-source-id: 08c236059798c710db9cbf545fce0f371232d447

db/column_family.cc

@@ -129,14 +129,10 @@ Status CheckCompressionSupported(const ColumnFamilyOptions& cf_options) {
     }
   }
   if (cf_options.compression_opts.zstd_max_train_bytes > 0) {
-    if (!CompressionTypeSupported(CompressionType::kZSTD)) {
-      // Dictionary trainer is available since v0.6.1, but ZSTD was marked
-      // stable only since v0.8.0. For now we enable the feature in stable
-      // versions only.
+    if (!ZSTD_TrainDictionarySupported()) {
       return Status::InvalidArgument(
-          "zstd dictionary trainer cannot be used because " +
-          CompressionTypeToString(CompressionType::kZSTD) +
-          " is not linked with the binary.");
+          "zstd dictionary trainer cannot be used because ZSTD 1.1.3+ "
+          "is not linked with the binary.");
     }
     if (cf_options.compression_opts.max_dict_bytes == 0) {
       return Status::InvalidArgument(

db/db_test2.cc

@@ -3214,6 +3214,57 @@ TEST_F(DBTest2, TestCompactFiles) {
 }
 #endif  // ROCKSDB_LITE
 
+// TODO: figure out why this test fails in appveyor
+#ifndef OS_WIN
+TEST_F(DBTest2, MultiDBParallelOpenTest) {
+  const int kNumDbs = 2;
+  Options options = CurrentOptions();
+  std::vector<std::string> dbnames;
+  for (int i = 0; i < kNumDbs; ++i) {
+    dbnames.emplace_back(test::TmpDir(env_) + "/db" + ToString(i));
+    ASSERT_OK(DestroyDB(dbnames.back(), options));
+  }
+
+  // Verify empty DBs can be created in parallel
+  std::vector<std::thread> open_threads;
+  std::vector<DB*> dbs{static_cast<unsigned int>(kNumDbs), nullptr};
+  options.create_if_missing = true;
+  for (int i = 0; i < kNumDbs; ++i) {
+    open_threads.emplace_back(
+        [&](int dbnum) {
+          ASSERT_OK(DB::Open(options, dbnames[dbnum], &dbs[dbnum]));
+        },
+        i);
+  }
+
+  // Now add some data and close, so next we can verify non-empty DBs can be
+  // recovered in parallel
+  for (int i = 0; i < kNumDbs; ++i) {
+    open_threads[i].join();
+    ASSERT_OK(dbs[i]->Put(WriteOptions(), "xi", "gua"));
+    delete dbs[i];
+  }
+
+  // Verify non-empty DBs can be recovered in parallel
+  dbs.clear();
+  open_threads.clear();
+  for (int i = 0; i < kNumDbs; ++i) {
+    open_threads.emplace_back(
+        [&](int dbnum) {
+          ASSERT_OK(DB::Open(options, dbnames[dbnum], &dbs[dbnum]));
+        },
+        i);
+  }
+
+  // Wait and cleanup
+  for (int i = 0; i < kNumDbs; ++i) {
+    open_threads[i].join();
+    delete dbs[i];
+    ASSERT_OK(DestroyDB(dbnames[i], options));
+  }
+}
+#endif  // OS_WIN
+
 }  // namespace rocksdb
 
 int main(int argc, char** argv) {

table/block_based_table_builder.cc

@@ -104,19 +104,19 @@ bool GoodCompressionRatio(size_t compressed_size, size_t raw_size) {
 }  // namespace
 
 // format_version is the block format as defined in include/rocksdb/table.h
-Slice CompressBlock(const Slice& raw, const CompressionContext& compression_ctx,
+Slice CompressBlock(const Slice& raw, const CompressionInfo& compression_info,
                     CompressionType* type, uint32_t format_version,
                     std::string* compressed_output) {
-  *type = compression_ctx.type();
-  if (compression_ctx.type() == kNoCompression) {
+  *type = compression_info.type();
+  if (compression_info.type() == kNoCompression) {
     return raw;
   }
 
   // Will return compressed block contents if (1) the compression method is
   // supported in this platform and (2) the compression rate is "good enough".
-  switch (compression_ctx.type()) {
+  switch (compression_info.type()) {
     case kSnappyCompression:
-      if (Snappy_Compress(compression_ctx, raw.data(), raw.size(),
+      if (Snappy_Compress(compression_info, raw.data(), raw.size(),
                           compressed_output) &&
           GoodCompressionRatio(compressed_output->size(), raw.size())) {
         return *compressed_output;
@@ -124,7 +124,7 @@ Slice CompressBlock(const Slice& raw, const CompressionContext& compression_ctx,
       break;  // fall back to no compression.
     case kZlibCompression:
       if (Zlib_Compress(
-              compression_ctx,
+              compression_info,
               GetCompressFormatForVersion(kZlibCompression, format_version),
               raw.data(), raw.size(), compressed_output) &&
           GoodCompressionRatio(compressed_output->size(), raw.size())) {
@@ -133,7 +133,7 @@ Slice CompressBlock(const Slice& raw, const CompressionContext& compression_ctx,
       break;  // fall back to no compression.
     case kBZip2Compression:
       if (BZip2_Compress(
-              compression_ctx,
+              compression_info,
               GetCompressFormatForVersion(kBZip2Compression, format_version),
               raw.data(), raw.size(), compressed_output) &&
           GoodCompressionRatio(compressed_output->size(), raw.size())) {
@@ -142,7 +142,7 @@ Slice CompressBlock(const Slice& raw, const CompressionContext& compression_ctx,
       break;  // fall back to no compression.
     case kLZ4Compression:
       if (LZ4_Compress(
-              compression_ctx,
+              compression_info,
               GetCompressFormatForVersion(kLZ4Compression, format_version),
               raw.data(), raw.size(), compressed_output) &&
           GoodCompressionRatio(compressed_output->size(), raw.size())) {
@@ -151,7 +151,7 @@ Slice CompressBlock(const Slice& raw, const CompressionContext& compression_ctx,
       break;  // fall back to no compression.
     case kLZ4HCCompression:
       if (LZ4HC_Compress(
-              compression_ctx,
+              compression_info,
               GetCompressFormatForVersion(kLZ4HCCompression, format_version),
               raw.data(), raw.size(), compressed_output) &&
           GoodCompressionRatio(compressed_output->size(), raw.size())) {
@@ -167,7 +167,7 @@ Slice CompressBlock(const Slice& raw, const CompressionContext& compression_ctx,
       break;
     case kZSTD:
     case kZSTDNotFinalCompression:
-      if (ZSTD_Compress(compression_ctx, raw.data(), raw.size(),
+      if (ZSTD_Compress(compression_info, raw.data(), raw.size(),
                         compressed_output) &&
           GoodCompressionRatio(compressed_output->size(), raw.size())) {
         return *compressed_output;
@@ -261,10 +261,12 @@ struct BlockBasedTableBuilder::Rep {
   PartitionedIndexBuilder* p_index_builder_ = nullptr;
 
   std::string last_key;
-  // Compression dictionary or nullptr
-  const std::string* compression_dict;
+  CompressionType compression_type;
+  CompressionOptions compression_opts;
+  CompressionDict compression_dict;
   CompressionContext compression_ctx;
   std::unique_ptr<UncompressionContext> verify_ctx;
+  UncompressionDict verify_dict;
   TableProperties props;
 
   bool closed = false;  // Either Finish() or Abandon() has been called.
@@ -313,8 +315,15 @@ struct BlockBasedTableBuilder::Rep {
                    table_options.data_block_hash_table_util_ratio),
         range_del_block(1 /* block_restart_interval */),
         internal_prefix_transform(_moptions.prefix_extractor.get()),
-        compression_dict(_compression_dict),
-        compression_ctx(_compression_type, _compression_opts),
+        compression_type(_compression_type),
+        compression_opts(_compression_opts),
+        compression_dict(
+            _compression_dict == nullptr ? Slice() : Slice(*_compression_dict),
+            _compression_type, _compression_opts.level),
+        compression_ctx(_compression_type),
+        verify_dict(
+            _compression_dict == nullptr ? Slice() : Slice(*_compression_dict),
+            _compression_type),
         use_delta_encoding_for_index_values(table_opt.format_version >= 4 &&
                                             !table_opt.block_align),
         compressed_cache_key_prefix_size(0),
@@ -355,7 +364,7 @@ struct BlockBasedTableBuilder::Rep {
             _moptions.prefix_extractor != nullptr));
     if (table_options.verify_compression) {
       verify_ctx.reset(new UncompressionContext(UncompressionContext::NoCache(),
-                                                compression_ctx.type()));
+                                                compression_type));
     }
   }
 
@@ -506,7 +515,7 @@ void BlockBasedTableBuilder::WriteBlock(const Slice& raw_block_contents,
   assert(ok());
   Rep* r = rep_;
 
-  auto type = r->compression_ctx.type();
+  auto type = r->compression_type;
   Slice block_contents;
   bool abort_compression = false;
 
@@ -514,24 +523,12 @@ void BlockBasedTableBuilder::WriteBlock(const Slice& raw_block_contents,
     ShouldReportDetailedTime(r->ioptions.env, r->ioptions.statistics));
 
   if (raw_block_contents.size() < kCompressionSizeLimit) {
-    Slice compression_dict;
-    if (is_data_block && r->compression_dict && r->compression_dict->size()) {
-      r->compression_ctx.dict() = *r->compression_dict;
-      if (r->table_options.verify_compression) {
-        assert(r->verify_ctx != nullptr);
-        r->verify_ctx->dict() = *r->compression_dict;
-      }
-    } else {
-      // Clear dictionary
-      r->compression_ctx.dict() = Slice();
-      if (r->table_options.verify_compression) {
-        assert(r->verify_ctx != nullptr);
-        r->verify_ctx->dict() = Slice();
-      }
-    }
-
+    CompressionInfo compression_info(
+        r->compression_opts, r->compression_ctx,
+        is_data_block ? r->compression_dict : CompressionDict::GetEmptyDict(),
+        r->compression_type);
     block_contents =
-        CompressBlock(raw_block_contents, r->compression_ctx, &type,
+        CompressBlock(raw_block_contents, compression_info, &type,
                       r->table_options.format_version, &r->compressed_output);
 
     // Some of the compression algorithms are known to be unreliable. If
@@ -540,8 +537,12 @@ void BlockBasedTableBuilder::WriteBlock(const Slice& raw_block_contents,
     if (type != kNoCompression && r->table_options.verify_compression) {
       // Retrieve the uncompressed contents into a new buffer
       BlockContents contents;
+      UncompressionInfo uncompression_info(
+          *r->verify_ctx,
+          is_data_block ? r->verify_dict : UncompressionDict::GetEmptyDict(),
+          r->compression_type);
       Status stat = UncompressBlockContentsForCompressionType(
-          *r->verify_ctx, block_contents.data(), block_contents.size(),
+          uncompression_info, block_contents.data(), block_contents.size(),
           &contents, r->table_options.format_version, r->ioptions);
 
       if (stat.ok()) {
@@ -805,7 +806,7 @@ void BlockBasedTableBuilder::WritePropertiesBlock(
             ? rep_->ioptions.merge_operator->Name()
             : "nullptr";
     rep_->props.compression_name =
-        CompressionTypeToString(rep_->compression_ctx.type());
+        CompressionTypeToString(rep_->compression_type);
     rep_->props.prefix_extractor_name =
         rep_->moptions.prefix_extractor != nullptr
             ? rep_->moptions.prefix_extractor->Name()
@@ -854,10 +855,10 @@ void BlockBasedTableBuilder::WritePropertiesBlock(
 
 void BlockBasedTableBuilder::WriteCompressionDictBlock(
     MetaIndexBuilder* meta_index_builder) {
-  if (rep_->compression_dict && rep_->compression_dict->size()) {
+  if (rep_->compression_dict.GetRawDict().size()) {
     BlockHandle compression_dict_block_handle;
     if (ok()) {
-      WriteRawBlock(*rep_->compression_dict, kNoCompression,
+      WriteRawBlock(rep_->compression_dict.GetRawDict(), kNoCompression,
                     &compression_dict_block_handle);
     }
     if (ok()) {

table/block_based_table_builder.h

@@ -133,7 +133,7 @@ class BlockBasedTableBuilder : public TableBuilder {
   const uint64_t kCompressionSizeLimit = std::numeric_limits<int>::max();
 };
 
-Slice CompressBlock(const Slice& raw, const CompressionContext& compression_ctx,
+Slice CompressBlock(const Slice& raw, const CompressionInfo& info,
                     CompressionType* type, uint32_t format_version,
                     std::string* compressed_output);
 

table/block_based_table_reader.cc

@@ -1334,8 +1334,10 @@ Status BlockBasedTable::GetDataBlockFromCache(
 
   // Retrieve the uncompressed contents into a new buffer
   BlockContents contents;
-  UncompressionContext uncompresssion_ctx(compression_type, compression_dict);
-  s = UncompressBlockContents(uncompresssion_ctx, compressed_block->data.data(),
+  UncompressionContext context(compression_type);
+  UncompressionDict dict(compression_dict, compression_type);
+  UncompressionInfo info(context, dict, compression_type);
+  s = UncompressBlockContents(info, compressed_block->data.data(),
                               compressed_block->data.size(), &contents,
                               rep->table_options.format_version, rep->ioptions,
                               GetMemoryAllocator(rep->table_options));
@@ -1412,12 +1414,13 @@ Status BlockBasedTable::PutDataBlockToCache(
   BlockContents uncompressed_block_contents;
   Statistics* statistics = ioptions.statistics;
   if (raw_block_comp_type != kNoCompression) {
-    UncompressionContext uncompression_ctx(raw_block_comp_type,
-                                           compression_dict);
-    s = UncompressBlockContents(
-        uncompression_ctx, raw_block_contents->data.data(),
-        raw_block_contents->data.size(), &uncompressed_block_contents,
-        format_version, ioptions, memory_allocator);
+    UncompressionContext context(raw_block_comp_type);
+    UncompressionDict dict(compression_dict, raw_block_comp_type);
+    UncompressionInfo info(context, dict, raw_block_comp_type);
+    s = UncompressBlockContents(info, raw_block_contents->data.data(),
+                                raw_block_contents->data.size(),
+                                &uncompressed_block_contents, format_version,
+                                ioptions, memory_allocator);
   }
   if (!s.ok()) {
     return s;

table/block_fetcher.cc

@@ -256,11 +256,12 @@ Status BlockFetcher::ReadBlockContents() {
 
   if (do_uncompress_ && compression_type_ != kNoCompression) {
     // compressed page, uncompress, update cache
-    UncompressionContext uncompression_ctx(compression_type_,
-                                           compression_dict_);
-    status_ = UncompressBlockContents(uncompression_ctx, slice_.data(),
-                                      block_size_, contents_, footer_.version(),
-                                      ioptions_, memory_allocator_);
+    UncompressionContext context(compression_type_);
+    UncompressionDict dict(compression_dict_, compression_type_);
+    UncompressionInfo info(context, dict, compression_type_);
+    status_ = UncompressBlockContents(info, slice_.data(), block_size_,
+                                      contents_, footer_.version(), ioptions_,
+                                      memory_allocator_);
     compression_type_ = kNoCompression;
   } else {
     GetBlockContents();

table/format.cc

@@ -278,18 +278,18 @@ Status ReadFooterFromFile(RandomAccessFileReader* file,
 }
 
 Status UncompressBlockContentsForCompressionType(
-    const UncompressionContext& uncompression_ctx, const char* data, size_t n,
+    const UncompressionInfo& uncompression_info, const char* data, size_t n,
     BlockContents* contents, uint32_t format_version,
     const ImmutableCFOptions& ioptions, MemoryAllocator* allocator) {
   CacheAllocationPtr ubuf;
 
-  assert(uncompression_ctx.type() != kNoCompression &&
+  assert(uncompression_info.type() != kNoCompression &&
          "Invalid compression type");
 
   StopWatchNano timer(ioptions.env,
     ShouldReportDetailedTime(ioptions.env, ioptions.statistics));
   int decompress_size = 0;
-  switch (uncompression_ctx.type()) {
+  switch (uncompression_info.type()) {
     case kSnappyCompression: {
       size_t ulength = 0;
       static char snappy_corrupt_msg[] =
@@ -306,7 +306,7 @@ Status UncompressBlockContentsForCompressionType(
     }
     case kZlibCompression:
       ubuf = Zlib_Uncompress(
-          uncompression_ctx, data, n, &decompress_size,
+          uncompression_info, data, n, &decompress_size,
           GetCompressFormatForVersion(kZlibCompression, format_version),
           allocator);
       if (!ubuf) {
@@ -330,7 +330,7 @@ Status UncompressBlockContentsForCompressionType(
       break;
     case kLZ4Compression:
       ubuf = LZ4_Uncompress(
-          uncompression_ctx, data, n, &decompress_size,
+          uncompression_info, data, n, &decompress_size,
           GetCompressFormatForVersion(kLZ4Compression, format_version),
           allocator);
       if (!ubuf) {
@@ -342,7 +342,7 @@ Status UncompressBlockContentsForCompressionType(
       break;
     case kLZ4HCCompression:
       ubuf = LZ4_Uncompress(
-          uncompression_ctx, data, n, &decompress_size,
+          uncompression_info, data, n, &decompress_size,
           GetCompressFormatForVersion(kLZ4HCCompression, format_version),
           allocator);
       if (!ubuf) {
@@ -365,7 +365,7 @@ Status UncompressBlockContentsForCompressionType(
       break;
     case kZSTD:
     case kZSTDNotFinalCompression:
-      ubuf = ZSTD_Uncompress(uncompression_ctx, data, n, &decompress_size,
+      ubuf = ZSTD_Uncompress(uncompression_info, data, n, &decompress_size,
                              allocator);
       if (!ubuf) {
         static char zstd_corrupt_msg[] =
@@ -395,14 +395,14 @@ Status UncompressBlockContentsForCompressionType(
 // buffer is returned via 'result' and it is upto the caller to
 // free this buffer.
 // format_version is the block format as defined in include/rocksdb/table.h
-Status UncompressBlockContents(const UncompressionContext& uncompression_ctx,
+Status UncompressBlockContents(const UncompressionInfo& uncompression_info,
                                const char* data, size_t n,
                                BlockContents* contents, uint32_t format_version,
                                const ImmutableCFOptions& ioptions,
                                MemoryAllocator* allocator) {
   assert(data[n] != kNoCompression);
-  assert(data[n] == uncompression_ctx.type());
-  return UncompressBlockContentsForCompressionType(uncompression_ctx, data, n,
+  assert(data[n] == uncompression_info.type());
+  return UncompressBlockContentsForCompressionType(uncompression_info, data, n,
                                                    contents, format_version,
                                                    ioptions, allocator);
 }

table/format.h

@@ -277,16 +277,18 @@ extern Status ReadBlockContents(
 // free this buffer.
 // For description of compress_format_version and possible values, see
 // util/compression.h
-extern Status UncompressBlockContents(
-    const UncompressionContext& uncompression_ctx, const char* data, size_t n,
-    BlockContents* contents, uint32_t compress_format_version,
-    const ImmutableCFOptions& ioptions, MemoryAllocator* allocator = nullptr);
+extern Status UncompressBlockContents(const UncompressionInfo& info,
+                                      const char* data, size_t n,
+                                      BlockContents* contents,
+                                      uint32_t compress_format_version,
+                                      const ImmutableCFOptions& ioptions,
+                                      MemoryAllocator* allocator = nullptr);
 
 // This is an extension to UncompressBlockContents that accepts
 // a specific compression type. This is used by un-wrapped blocks
 // with no compression header.
 extern Status UncompressBlockContentsForCompressionType(
-    const UncompressionContext& uncompression_ctx, const char* data, size_t n,
+    const UncompressionInfo& info, const char* data, size_t n,
     BlockContents* contents, uint32_t compress_format_version,
     const ImmutableCFOptions& ioptions, MemoryAllocator* allocator = nullptr);
 

tools/db_bench_tool.cc

@@ -2051,28 +2051,28 @@ class Benchmark {
     return true;
   }
 
-  inline bool CompressSlice(const CompressionContext& compression_ctx,
+  inline bool CompressSlice(const CompressionInfo& compression_info,
                             const Slice& input, std::string* compressed) {
     bool ok = true;
     switch (FLAGS_compression_type_e) {
       case rocksdb::kSnappyCompression:
-        ok = Snappy_Compress(compression_ctx, input.data(), input.size(),
+        ok = Snappy_Compress(compression_info, input.data(), input.size(),
                              compressed);
         break;
       case rocksdb::kZlibCompression:
-        ok = Zlib_Compress(compression_ctx, 2, input.data(), input.size(),
+        ok = Zlib_Compress(compression_info, 2, input.data(), input.size(),
                            compressed);
         break;
       case rocksdb::kBZip2Compression:
-        ok = BZip2_Compress(compression_ctx, 2, input.data(), input.size(),
+        ok = BZip2_Compress(compression_info, 2, input.data(), input.size(),
                             compressed);
         break;
       case rocksdb::kLZ4Compression:
-        ok = LZ4_Compress(compression_ctx, 2, input.data(), input.size(),
+        ok = LZ4_Compress(compression_info, 2, input.data(), input.size(),
                           compressed);
         break;
       case rocksdb::kLZ4HCCompression:
-        ok = LZ4HC_Compress(compression_ctx, 2, input.data(), input.size(),
+        ok = LZ4HC_Compress(compression_info, 2, input.data(), input.size(),
                             compressed);
         break;
       case rocksdb::kXpressCompression:
@@ -2080,7 +2080,7 @@ class Benchmark {
           input.size(), compressed);
         break;
       case rocksdb::kZSTD:
-        ok = ZSTD_Compress(compression_ctx, input.data(), input.size(),
+        ok = ZSTD_Compress(compression_info, input.data(), input.size(),
                            compressed);
         break;
       default:
@@ -2163,10 +2163,11 @@ class Benchmark {
       const int len = FLAGS_block_size;
       std::string input_str(len, 'y');
       std::string compressed;
-      CompressionContext compression_ctx(FLAGS_compression_type_e,
-                                         Options().compression_opts);
-      bool result =
-          CompressSlice(compression_ctx, Slice(input_str), &compressed);
+      CompressionOptions opts;
+      CompressionContext context(FLAGS_compression_type_e);
+      CompressionInfo info(opts, context, CompressionDict::GetEmptyDict(),
+                           FLAGS_compression_type_e);
+      bool result = CompressSlice(info, Slice(input_str), &compressed);
 
       if (!result) {
         fprintf(stdout, "WARNING: %s compression is not enabled\n",
@@ -3020,13 +3021,14 @@ void VerifyDBFromDB(std::string& truth_db_name) {
     int64_t produced = 0;
     bool ok = true;
     std::string compressed;
-    CompressionContext compression_ctx(FLAGS_compression_type_e,
-                                       Options().compression_opts);
-
+    CompressionOptions opts;
+    CompressionContext context(FLAGS_compression_type_e);
+    CompressionInfo info(opts, context, CompressionDict::GetEmptyDict(),
+                         FLAGS_compression_type_e);
     // Compress 1G
     while (ok && bytes < int64_t(1) << 30) {
       compressed.clear();
-      ok = CompressSlice(compression_ctx, input, &compressed);
+      ok = CompressSlice(info, input, &compressed);
       produced += compressed.size();
       bytes += input.size();
       thread->stats.FinishedOps(nullptr, nullptr, 1, kCompress);
@@ -3048,11 +3050,17 @@ void VerifyDBFromDB(std::string& truth_db_name) {
     Slice input = gen.Generate(FLAGS_block_size);
     std::string compressed;
 
+    CompressionContext compression_ctx(FLAGS_compression_type_e);
+    CompressionOptions compression_opts;
+    CompressionInfo compression_info(compression_opts, compression_ctx,
+                                     CompressionDict::GetEmptyDict(),
+                                     FLAGS_compression_type_e);
     UncompressionContext uncompression_ctx(FLAGS_compression_type_e);
-    CompressionContext compression_ctx(FLAGS_compression_type_e,
-                                       Options().compression_opts);
+    UncompressionInfo uncompression_info(uncompression_ctx,
+                                         UncompressionDict::GetEmptyDict(),
+                                         FLAGS_compression_type_e);
 
-    bool ok = CompressSlice(compression_ctx, input, &compressed);
+    bool ok = CompressSlice(compression_info, input, &compressed);
     int64_t bytes = 0;
     int decompress_size;
     while (ok && bytes < 1024 * 1048576) {
@@ -3072,7 +3080,7 @@ void VerifyDBFromDB(std::string& truth_db_name) {
           break;
         }
       case rocksdb::kZlibCompression:
-        uncompressed = Zlib_Uncompress(uncompression_ctx, compressed.data(),
+        uncompressed = Zlib_Uncompress(uncompression_info, compressed.data(),
                                        compressed.size(), &decompress_size, 2);
         ok = uncompressed.get() != nullptr;
         break;
@@ -3082,12 +3090,12 @@ void VerifyDBFromDB(std::string& truth_db_name) {
         ok = uncompressed.get() != nullptr;
         break;
       case rocksdb::kLZ4Compression:
-        uncompressed = LZ4_Uncompress(uncompression_ctx, compressed.data(),
+        uncompressed = LZ4_Uncompress(uncompression_info, compressed.data(),
                                       compressed.size(), &decompress_size, 2);
         ok = uncompressed.get() != nullptr;
         break;
       case rocksdb::kLZ4HCCompression:
-        uncompressed = LZ4_Uncompress(uncompression_ctx, compressed.data(),
+        uncompressed = LZ4_Uncompress(uncompression_info, compressed.data(),
                                       compressed.size(), &decompress_size, 2);
         ok = uncompressed.get() != nullptr;
         break;
@@ -3097,7 +3105,7 @@ void VerifyDBFromDB(std::string& truth_db_name) {
         ok = uncompressed.get() != nullptr;
         break;
       case rocksdb::kZSTD:
-        uncompressed = ZSTD_Uncompress(uncompression_ctx, compressed.data(),
+        uncompressed = ZSTD_Uncompress(uncompression_info, compressed.data(),
                                        compressed.size(), &decompress_size);
         ok = uncompressed.get() != nullptr;
         break;

util/compression.h

@@ -135,12 +135,127 @@ class ZSTDUncompressCachedData {
 
 namespace rocksdb {
 
-// Instantiate this class and pass it to the uncompression API below
+// Holds dictionary and related data, like ZSTD's digested compression
+// dictionary.
+struct CompressionDict {
+#if ZSTD_VERSION_NUMBER >= 700
+  ZSTD_CDict* zstd_cdict_ = nullptr;
+#endif  // ZSTD_VERSION_NUMBER >= 700
+  Slice dict_;
+
+ public:
+#if ZSTD_VERSION_NUMBER >= 700
+  CompressionDict(Slice dict, CompressionType type, int level) {
+#else   // ZSTD_VERSION_NUMBER >= 700
+  CompressionDict(Slice dict, CompressionType /*type*/, int /*level*/) {
+#endif  // ZSTD_VERSION_NUMBER >= 700
+    dict_ = std::move(dict);
+#if ZSTD_VERSION_NUMBER >= 700
+    zstd_cdict_ = nullptr;
+    if (!dict_.empty() && (type == kZSTD || type == kZSTDNotFinalCompression)) {
+      if (level == CompressionOptions::kDefaultCompressionLevel) {
+        // 3 is the value of ZSTD_CLEVEL_DEFAULT (not exposed publicly), see
+        // https://github.com/facebook/zstd/issues/1148
+        level = 3;
+      }
+      // Should be safe (but slower) if below call fails as we'll use the
+      // raw dictionary to compress.
+      zstd_cdict_ = ZSTD_createCDict(dict_.data(), dict_.size(), level);
+      assert(zstd_cdict_ != nullptr);
+    }
+#endif  // ZSTD_VERSION_NUMBER >= 700
+  }
+
+  ~CompressionDict() {
+#if ZSTD_VERSION_NUMBER >= 700
+    size_t res = 0;
+    if (zstd_cdict_ != nullptr) {
+      res = ZSTD_freeCDict(zstd_cdict_);
+    }
+    assert(res == 0);  // Last I checked they can't fail
+    (void)res;         // prevent unused var warning
+#endif                 // ZSTD_VERSION_NUMBER >= 700
+  }
+
+#if ZSTD_VERSION_NUMBER >= 700
+  const ZSTD_CDict* GetDigestedZstdCDict() const {
+    return zstd_cdict_;
+  }
+#endif  // ZSTD_VERSION_NUMBER >= 700
+
+  Slice GetRawDict() const { return dict_; }
+
+  static const CompressionDict& GetEmptyDict() {
+    static CompressionDict empty_dict{};
+    return empty_dict;
+  }
+
+  CompressionDict() = default;
+  // Disable copy/move
+  CompressionDict(const CompressionDict&) = delete;
+  CompressionDict& operator=(const CompressionDict&) = delete;
+  CompressionDict(CompressionDict&&) = delete;
+  CompressionDict& operator=(CompressionDict&&) = delete;
+};
+
+// Holds dictionary and related data, like ZSTD's digested uncompression
+// dictionary.
+struct UncompressionDict {
+#if ZSTD_VERSION_NUMBER >= 700
+  ZSTD_DDict* zstd_ddict_;
+#endif  // ZSTD_VERSION_NUMBER >= 700
+  Slice dict_;
+
+#if ZSTD_VERSION_NUMBER >= 700
+  UncompressionDict(Slice dict, CompressionType type) {
+#else   // ZSTD_VERSION_NUMBER >= 700
+  UncompressionDict(Slice dict, CompressionType /*type*/) {
+#endif  // ZSTD_VERSION_NUMBER >= 700
+    dict_ = std::move(dict);
+#if ZSTD_VERSION_NUMBER >= 700
+    zstd_ddict_ = nullptr;
+    if (!dict_.empty() && (type == kZSTD || type == kZSTDNotFinalCompression)) {
+      zstd_ddict_ = ZSTD_createDDict(dict_.data(), dict_.size());
+      assert(zstd_ddict_ != nullptr);
+    }
+#endif  // ZSTD_VERSION_NUMBER >= 700
+  }
+
+  ~UncompressionDict() {
+#if ZSTD_VERSION_NUMBER >= 700
+    size_t res = 0;
+    if (zstd_ddict_ != nullptr) {
+      res = ZSTD_freeDDict(zstd_ddict_);
+    }
+    assert(res == 0);  // Last I checked they can't fail
+    (void)res;         // prevent unused var warning
+#endif                 // ZSTD_VERSION_NUMBER >= 700
+  }
+
+#if ZSTD_VERSION_NUMBER >= 700
+  const ZSTD_DDict* GetDigestedZstdDDict() const {
+    return zstd_ddict_;
+  }
+#endif  // ZSTD_VERSION_NUMBER >= 700
+
+  Slice GetRawDict() const { return dict_; }
+
+  static const UncompressionDict& GetEmptyDict() {
+    static UncompressionDict empty_dict{};
+    return empty_dict;
+  }
+
+  UncompressionDict() = default;
+  // Disable copy/move
+  UncompressionDict(const CompressionDict&) = delete;
+  UncompressionDict& operator=(const CompressionDict&) = delete;
+  UncompressionDict(CompressionDict&&) = delete;
+  UncompressionDict& operator=(CompressionDict&&) = delete;
+};
+
 class CompressionContext {
  private:
   const CompressionType type_;
-  const CompressionOptions opts_;
-  Slice dict_;
 #if defined(ZSTD) && (ZSTD_VERSION_NUMBER >= 500)
   ZSTD_CCtx* zstd_ctx_ = nullptr;
   void CreateNativeContext() {
@@ -165,6 +280,7 @@ class CompressionContext {
     assert(type_ == kZSTD || type_ == kZSTDNotFinalCompression);
     return zstd_ctx_;
   }
+
 #else   // ZSTD && (ZSTD_VERSION_NUMBER >= 500)
  private:
   void CreateNativeContext() {}
@@ -172,28 +288,35 @@ class CompressionContext {
 #endif  // ZSTD && (ZSTD_VERSION_NUMBER >= 500)
  public:
   explicit CompressionContext(CompressionType comp_type) : type_(comp_type) {
-    CreateNativeContext();
-  }
-  CompressionContext(CompressionType comp_type, const CompressionOptions& opts,
-                     const Slice& comp_dict = Slice())
-      : type_(comp_type), opts_(opts), dict_(comp_dict) {
+    (void)type_;
     CreateNativeContext();
   }
   ~CompressionContext() { DestroyNativeContext(); }
   CompressionContext(const CompressionContext&) = delete;
   CompressionContext& operator=(const CompressionContext&) = delete;
+};
+
+class CompressionInfo {
+  const CompressionOptions& opts_;
+  const CompressionContext& context_;
+  const CompressionDict& dict_;
+  const CompressionType type_;
+
+ public:
+  CompressionInfo(const CompressionOptions& _opts,
+                  const CompressionContext& _context,
+                  const CompressionDict& _dict, CompressionType _type)
+      : opts_(_opts), context_(_context), dict_(_dict), type_(_type) {}
 
   const CompressionOptions& options() const { return opts_; }
+  const CompressionContext& context() const { return context_; }
+  const CompressionDict& dict() const { return dict_; }
   CompressionType type() const { return type_; }
-  const Slice& dict() const { return dict_; }
-  Slice& dict() { return dict_; }
 };
 
-// Instantiate this class and pass it to the uncompression API below
 class UncompressionContext {
  private:
-  CompressionType type_;
-  Slice dict_;
+  const CompressionType type_;
   CompressionContextCache* ctx_cache_ = nullptr;
   ZSTDUncompressCachedData uncomp_cached_data_;
 
@@ -201,10 +324,8 @@ class UncompressionContext {
   struct NoCache {};
   // Do not use context cache, used by TableBuilder
   UncompressionContext(NoCache, CompressionType comp_type) : type_(comp_type) {}
-  explicit UncompressionContext(CompressionType comp_type)
-      : UncompressionContext(comp_type, Slice()) {}
-  UncompressionContext(CompressionType comp_type, const Slice& comp_dict)
-      : type_(comp_type), dict_(comp_dict) {
+
+  explicit UncompressionContext(CompressionType comp_type) : type_(comp_type) {
     if (type_ == kZSTD || type_ == kZSTDNotFinalCompression) {
       ctx_cache_ = CompressionContextCache::Instance();
       uncomp_cached_data_ = ctx_cache_->GetCachedZSTDUncompressData();
@@ -224,9 +345,21 @@ class UncompressionContext {
   ZSTDUncompressCachedData::ZSTDNativeContext GetZSTDContext() const {
     return uncomp_cached_data_.Get();
   }
+};
+
+class UncompressionInfo {
+  const UncompressionContext& context_;
+  const UncompressionDict& dict_;
+  const CompressionType type_;
+
+ public:
+  UncompressionInfo(const UncompressionContext& _context,
+                    const UncompressionDict& _dict, CompressionType _type)
+      : context_(_context), dict_(_dict), type_(_type) {}
+
+  const UncompressionContext& context() const { return context_; }
+  const UncompressionDict& dict() const { return dict_; }
   CompressionType type() const { return type_; }
-  const Slice& dict() const { return dict_; }
-  Slice& dict() { return dict_; }
 };
 
 inline bool Snappy_Supported() {
@@ -345,9 +478,8 @@ inline std::string CompressionTypeToString(CompressionType compression_type) {
 // 2 -- Zlib, BZip2 and LZ4 encode decompressed size as Varint32 just before the
 // start of compressed block. Snappy format is the same as version 1.
 
-inline bool Snappy_Compress(const CompressionContext& /*ctx*/,
-                            const char* input, size_t length,
-                            ::std::string* output) {
+inline bool Snappy_Compress(const CompressionInfo& /*info*/, const char* input,
+                            size_t length, ::std::string* output) {
 #ifdef SNAPPY
   output->resize(snappy::MaxCompressedLength(length));
   size_t outlen;
@@ -412,7 +544,7 @@ inline bool GetDecompressedSizeInfo(const char** input_data,
 // header in varint32 format
 // @param compression_dict Data for presetting the compression library's
 //    dictionary.
-inline bool Zlib_Compress(const CompressionContext& ctx,
+inline bool Zlib_Compress(const CompressionInfo& info,
                           uint32_t compress_format_version, const char* input,
                           size_t length, ::std::string* output) {
 #ifdef ZLIB
@@ -437,24 +569,25 @@ inline bool Zlib_Compress(const CompressionContext& ctx,
   // The default value is 8. See zconf.h for more details.
   static const int memLevel = 8;
   int level;
-  if (ctx.options().level == CompressionOptions::kDefaultCompressionLevel) {
+  if (info.options().level == CompressionOptions::kDefaultCompressionLevel) {
     level = Z_DEFAULT_COMPRESSION;
   } else {
-    level = ctx.options().level;
+    level = info.options().level;
   }
   z_stream _stream;
   memset(&_stream, 0, sizeof(z_stream));
-  int st = deflateInit2(&_stream, level, Z_DEFLATED, ctx.options().window_bits,
-                        memLevel, ctx.options().strategy);
+  int st = deflateInit2(&_stream, level, Z_DEFLATED, info.options().window_bits,
+                        memLevel, info.options().strategy);
   if (st != Z_OK) {
     return false;
   }
 
-  if (ctx.dict().size()) {
+  Slice compression_dict = info.dict().GetRawDict();
+  if (compression_dict.size()) {
     // Initialize the compression library's dictionary
-    st = deflateSetDictionary(&_stream,
-                              reinterpret_cast<const Bytef*>(ctx.dict().data()),
-                              static_cast<unsigned int>(ctx.dict().size()));
+    st = deflateSetDictionary(
+        &_stream, reinterpret_cast<const Bytef*>(compression_dict.data()),
+        static_cast<unsigned int>(compression_dict.size()));
     if (st != Z_OK) {
       deflateEnd(&_stream);
       return false;
@@ -482,7 +615,7 @@ inline bool Zlib_Compress(const CompressionContext& ctx,
   deflateEnd(&_stream);
   return compressed;
 #else
-  (void)ctx;
+  (void)info;
   (void)compress_format_version;
   (void)input;
   (void)length;
@@ -498,8 +631,8 @@ inline bool Zlib_Compress(const CompressionContext& ctx,
 // @param compression_dict Data for presetting the compression library's
 //    dictionary.
 inline CacheAllocationPtr Zlib_Uncompress(
-    const UncompressionContext& ctx, const char* input_data,
-    size_t input_length, int* decompress_size, uint32_t compress_format_version,
+    const UncompressionInfo& info, const char* input_data, size_t input_length,
+    int* decompress_size, uint32_t compress_format_version,
     MemoryAllocator* allocator = nullptr, int windowBits = -14) {
 #ifdef ZLIB
   uint32_t output_len = 0;
@@ -529,11 +662,12 @@ inline CacheAllocationPtr Zlib_Uncompress(
     return nullptr;
   }
 
-  if (ctx.dict().size()) {
+  Slice compression_dict = info.dict().GetRawDict();
+  if (compression_dict.size()) {
     // Initialize the compression library's dictionary
-    st = inflateSetDictionary(&_stream,
-                              reinterpret_cast<const Bytef*>(ctx.dict().data()),
-                              static_cast<unsigned int>(ctx.dict().size()));
+    st = inflateSetDictionary(
+        &_stream, reinterpret_cast<const Bytef*>(compression_dict.data()),
+        static_cast<unsigned int>(compression_dict.size()));
     if (st != Z_OK) {
       return nullptr;
     }
@@ -584,7 +718,7 @@ inline CacheAllocationPtr Zlib_Uncompress(
   inflateEnd(&_stream);
   return output;
 #else
-  (void)ctx;
+  (void)info;
   (void)input_data;
   (void)input_length;
   (void)decompress_size;
@@ -599,7 +733,7 @@ inline CacheAllocationPtr Zlib_Uncompress(
 // block header
 // compress_format_version == 2 -- decompressed size is included in the block
 // header in varint32 format
-inline bool BZip2_Compress(const CompressionContext& /*ctx*/,
+inline bool BZip2_Compress(const CompressionInfo& /*info*/,
                            uint32_t compress_format_version, const char* input,
                            size_t length, ::std::string* output) {
 #ifdef BZIP2
@@ -745,7 +879,7 @@ inline CacheAllocationPtr BZip2_Uncompress(
 // header in varint32 format
 // @param compression_dict Data for presetting the compression library's
 //    dictionary.
-inline bool LZ4_Compress(const CompressionContext& ctx,
+inline bool LZ4_Compress(const CompressionInfo& info,
                          uint32_t compress_format_version, const char* input,
                          size_t length, ::std::string* output) {
 #ifdef LZ4
@@ -773,9 +907,10 @@ inline bool LZ4_Compress(const CompressionContext& ctx,
   int outlen;
 #if LZ4_VERSION_NUMBER >= 10400  // r124+
   LZ4_stream_t* stream = LZ4_createStream();
-  if (ctx.dict().size()) {
-    LZ4_loadDict(stream, ctx.dict().data(),
-                 static_cast<int>(ctx.dict().size()));
+  Slice compression_dict = info.dict().GetRawDict();
+  if (compression_dict.size()) {
+    LZ4_loadDict(stream, compression_dict.data(),
+                 static_cast<int>(compression_dict.size()));
   }
 #if LZ4_VERSION_NUMBER >= 10700  // r129+
   outlen =
@@ -799,7 +934,7 @@ inline bool LZ4_Compress(const CompressionContext& ctx,
   output->resize(static_cast<size_t>(output_header_len + outlen));
   return true;
 #else  // LZ4
-  (void)ctx;
+  (void)info;
   (void)compress_format_version;
   (void)input;
   (void)length;
@@ -814,7 +949,7 @@ inline bool LZ4_Compress(const CompressionContext& ctx,
 // header in varint32 format
 // @param compression_dict Data for presetting the compression library's
 //    dictionary.
-inline CacheAllocationPtr LZ4_Uncompress(const UncompressionContext& ctx,
+inline CacheAllocationPtr LZ4_Uncompress(const UncompressionInfo& info,
                                          const char* input_data,
                                          size_t input_length,
                                          int* decompress_size,
@@ -842,9 +977,10 @@ inline CacheAllocationPtr LZ4_Uncompress(const UncompressionContext& ctx,
   auto output = AllocateBlock(output_len, allocator);
 #if LZ4_VERSION_NUMBER >= 10400  // r124+
   LZ4_streamDecode_t* stream = LZ4_createStreamDecode();
-  if (ctx.dict().size()) {
-    LZ4_setStreamDecode(stream, ctx.dict().data(),
-                        static_cast<int>(ctx.dict().size()));
+  Slice compression_dict = info.dict().GetRawDict();
+  if (compression_dict.size()) {
+    LZ4_setStreamDecode(stream, compression_dict.data(),
+                        static_cast<int>(compression_dict.size()));
   }
   *decompress_size = LZ4_decompress_safe_continue(
       stream, input_data, output.get(), static_cast<int>(input_length),
@@ -863,7 +999,7 @@ inline CacheAllocationPtr LZ4_Uncompress(const UncompressionContext& ctx,
   assert(*decompress_size == static_cast<int>(output_len));
   return output;
 #else  // LZ4
-  (void)ctx;
+  (void)info;
   (void)input_data;
   (void)input_length;
   (void)decompress_size;
@@ -879,7 +1015,7 @@ inline CacheAllocationPtr LZ4_Uncompress(const UncompressionContext& ctx,
 // header in varint32 format
 // @param compression_dict Data for presetting the compression library's
 //    dictionary.
-inline bool LZ4HC_Compress(const CompressionContext& ctx,
+inline bool LZ4HC_Compress(const CompressionInfo& info,
                            uint32_t compress_format_version, const char* input,
                            size_t length, ::std::string* output) {
 #ifdef LZ4
@@ -906,17 +1042,18 @@ inline bool LZ4HC_Compress(const CompressionContext& ctx,
 
   int outlen;
   int level;
-  if (ctx.options().level == CompressionOptions::kDefaultCompressionLevel) {
+  if (info.options().level == CompressionOptions::kDefaultCompressionLevel) {
     level = 0;  // lz4hc.h says any value < 1 will be sanitized to default
   } else {
-    level = ctx.options().level;
+    level = info.options().level;
   }
 #if LZ4_VERSION_NUMBER >= 10400  // r124+
   LZ4_streamHC_t* stream = LZ4_createStreamHC();
   LZ4_resetStreamHC(stream, level);
+  Slice compression_dict = info.dict().GetRawDict();
   const char* compression_dict_data =
-      ctx.dict().size() > 0 ? ctx.dict().data() : nullptr;
-  size_t compression_dict_size = ctx.dict().size();
+      compression_dict.size() > 0 ? compression_dict.data() : nullptr;
+  size_t compression_dict_size = compression_dict.size();
   LZ4_loadDictHC(stream, compression_dict_data,
                  static_cast<int>(compression_dict_size));
 
@@ -947,7 +1084,7 @@ inline bool LZ4HC_Compress(const CompressionContext& ctx,
   output->resize(static_cast<size_t>(output_header_len + outlen));
   return true;
 #else  // LZ4
-  (void)ctx;
+  (void)info;
   (void)compress_format_version;
   (void)input;
   (void)length;
@@ -981,9 +1118,7 @@ inline char* XPRESS_Uncompress(const char* /*input_data*/,
 }
 #endif
 
-// @param compression_dict Data for presetting the compression library's
-//    dictionary.
-inline bool ZSTD_Compress(const CompressionContext& ctx, const char* input,
+inline bool ZSTD_Compress(const CompressionInfo& info, const char* input,
                           size_t length, ::std::string* output) {
 #ifdef ZSTD
   if (length > std::numeric_limits<uint32_t>::max()) {
@@ -998,19 +1133,29 @@ inline bool ZSTD_Compress(const CompressionContext& ctx, const char* input,
   output->resize(static_cast<size_t>(output_header_len + compressBound));
   size_t outlen = 0;
   int level;
-  if (ctx.options().level == CompressionOptions::kDefaultCompressionLevel) {
+  if (info.options().level == CompressionOptions::kDefaultCompressionLevel) {
     // 3 is the value of ZSTD_CLEVEL_DEFAULT (not exposed publicly), see
     // https://github.com/facebook/zstd/issues/1148
     level = 3;
   } else {
-    level = ctx.options().level;
+    level = info.options().level;
   }
 #if ZSTD_VERSION_NUMBER >= 500  // v0.5.0+
-  ZSTD_CCtx* context = ctx.ZSTDPreallocCtx();
+  ZSTD_CCtx* context = info.context().ZSTDPreallocCtx();
   assert(context != nullptr);
+#if ZSTD_VERSION_NUMBER >= 700  // v0.7.0+
+  if (info.dict().GetDigestedZstdCDict() != nullptr) {
+    outlen = ZSTD_compress_usingCDict(context, &(*output)[output_header_len],
+                                      compressBound, input, length,
+                                      info.dict().GetDigestedZstdCDict());
+  }
+#endif  // ZSTD_VERSION_NUMBER >= 700
+  if (outlen == 0) {
     outlen = ZSTD_compress_usingDict(context, &(*output)[output_header_len],
                                      compressBound, input, length,
-                                   ctx.dict().data(), ctx.dict().size(), level);
+                                     info.dict().GetRawDict().data(),
+                                     info.dict().GetRawDict().size(), level);
+  }
 #else   // up to v0.4.x
   outlen = ZSTD_compress(&(*output)[output_header_len], compressBound, input,
                          length, level);
@@ -1021,7 +1166,7 @@ inline bool ZSTD_Compress(const CompressionContext& ctx, const char* input,
   output->resize(output_header_len + outlen);
   return true;
 #else  // ZSTD
-  (void)ctx;
+  (void)info;
   (void)input;
   (void)length;
   (void)output;
@@ -1032,9 +1177,8 @@ inline bool ZSTD_Compress(const CompressionContext& ctx, const char* input,
 // @param compression_dict Data for presetting the compression library's
 //    dictionary.
 inline CacheAllocationPtr ZSTD_Uncompress(
-    const UncompressionContext& ctx, const char* input_data,
-    size_t input_length, int* decompress_size,
-    MemoryAllocator* allocator = nullptr) {
+    const UncompressionInfo& info, const char* input_data, size_t input_length,
+    int* decompress_size, MemoryAllocator* allocator = nullptr) {
 #ifdef ZSTD
   uint32_t output_len = 0;
   if (!compression::GetDecompressedSizeInfo(&input_data, &input_length,
@@ -1043,14 +1187,24 @@ inline CacheAllocationPtr ZSTD_Uncompress(
   }
 
   auto output = AllocateBlock(output_len, allocator);
-  size_t actual_output_length;
+  size_t actual_output_length = 0;
 #if ZSTD_VERSION_NUMBER >= 500  // v0.5.0+
-  ZSTD_DCtx* context = ctx.GetZSTDContext();
+  ZSTD_DCtx* context = info.context().GetZSTDContext();
   assert(context != nullptr);
+#if ZSTD_VERSION_NUMBER >= 700  // v0.7.0+
+  if (info.dict().GetDigestedZstdDDict() != nullptr) {
+    actual_output_length = ZSTD_decompress_usingDDict(
+        context, output.get(), output_len, input_data, input_length,
+        info.dict().GetDigestedZstdDDict());
+  }
+#endif  // ZSTD_VERSION_NUMBER >= 700
+  if (actual_output_length == 0) {
     actual_output_length = ZSTD_decompress_usingDict(
         context, output.get(), output_len, input_data, input_length,
-      ctx.dict().data(), ctx.dict().size());
+        info.dict().GetRawDict().data(), info.dict().GetRawDict().size());
+  }
 #else   // up to v0.4.x
+  (void)info;
   actual_output_length =
       ZSTD_decompress(output.get(), output_len, input_data, input_length);
 #endif  // ZSTD_VERSION_NUMBER >= 500
@@ -1058,7 +1212,7 @@ inline CacheAllocationPtr ZSTD_Uncompress(
   *decompress_size = static_cast<int>(actual_output_length);
   return output;
 #else  // ZSTD
-  (void)ctx;
+  (void)info;
   (void)input_data;
   (void)input_length;
   (void)decompress_size;
@@ -1067,6 +1221,17 @@ inline CacheAllocationPtr ZSTD_Uncompress(
 #endif
 }
 
+inline bool ZSTD_TrainDictionarySupported() {
+#ifdef ZSTD
+  // Dictionary trainer is available since v0.6.1 for static linking, but not
+  // available for dynamic linking until v1.1.3. For now we enable the feature
+  // in v1.1.3+ only.
+  return (ZSTD_versionNumber() >= 10103);
+#else
+  return false;
+#endif
+}
+
 inline std::string ZSTD_TrainDictionary(const std::string& samples,
                                         const std::vector<size_t>& sample_lens,
                                         size_t max_dict_bytes) {
@@ -1074,6 +1239,10 @@ inline std::string ZSTD_TrainDictionary(const std::string& samples,
   // available for dynamic linking until v1.1.3. For now we enable the feature
   // in v1.1.3+ only.
 #if ZSTD_VERSION_NUMBER >= 10103  // v1.1.3+
+  assert(samples.empty() == sample_lens.empty());
+  if (samples.empty()) {
+    return "";
+  }
   std::string dict_data(max_dict_bytes, '\0');
   size_t dict_len = ZDICT_trainFromBuffer(
       &dict_data[0], max_dict_bytes, &samples[0], &sample_lens[0],

utilities/blob_db/blob_db_impl.cc

@@ -761,9 +761,11 @@ Slice BlobDBImpl::GetCompressedSlice(const Slice& raw,
     return raw;
   }
   StopWatch compression_sw(env_, statistics_, BLOB_DB_COMPRESSION_MICROS);
-  CompressionType ct = bdb_options_.compression;
-  CompressionContext compression_ctx(ct);
-  CompressBlock(raw, compression_ctx, &ct, kBlockBasedTableVersionFormat,
+  CompressionType type = bdb_options_.compression;
+  CompressionOptions opts;
+  CompressionContext context(type);
+  CompressionInfo info(opts, context, CompressionDict::GetEmptyDict(), type);
+  CompressBlock(raw, info, &type, kBlockBasedTableVersionFormat,
                 compression_output);
   return *compression_output;
 }
@@ -1100,9 +1102,11 @@ Status BlobDBImpl::GetBlobValue(const Slice& key, const Slice& index_entry,
     {
       StopWatch decompression_sw(env_, statistics_,
                                  BLOB_DB_DECOMPRESSION_MICROS);
-      UncompressionContext uncompression_ctx(bfile->compression());
+      UncompressionContext context(bfile->compression());
+      UncompressionInfo info(context, UncompressionDict::GetEmptyDict(),
+                             bfile->compression());
       s = UncompressBlockContentsForCompressionType(
-          uncompression_ctx, blob_value.data(), blob_value.size(), &contents,
+          info, blob_value.data(), blob_value.size(), &contents,
           kBlockBasedTableVersionFormat, *(cfh->cfd()->ioptions()));
     }
     value->PinSelf(contents.data);

utilities/blob_db/blob_dump_tool.cc

@@ -208,10 +208,13 @@ Status BlobDumpTool::DumpRecord(DisplayType show_key, DisplayType show_blob,
   if (compression != kNoCompression &&
       (show_uncompressed_blob != DisplayType::kNone || show_summary)) {
     BlockContents contents;
-    UncompressionContext uncompression_ctx(compression);
+    UncompressionContext context(compression);
+    UncompressionInfo info(context, UncompressionDict::GetEmptyDict(),
+                           compression);
     s = UncompressBlockContentsForCompressionType(
-        uncompression_ctx, slice.data() + key_size, static_cast<size_t>(value_size),
-        &contents, 2 /*compress_format_version*/, ImmutableCFOptions(Options()));
+        info, slice.data() + key_size, static_cast<size_t>(value_size),
+        &contents, 2 /*compress_format_version*/,
+        ImmutableCFOptions(Options()));
     if (!s.ok()) {
       return s;
     }