fix db_stress test

Summary: Fix the db_stress test, let is run with HashSkipList for real

Test Plan:
python tools/db_crashtest.py
python tools/db_crashtest2.py

Reviewers: igor, haobo

Reviewed By: igor

CC: leveldb

Differential Revision: https://reviews.facebook.net/D16773

tools/db_crashtest.py

@@ -93,6 +93,8 @@ def main(argv):
             --max_background_compactions=20
             --max_bytes_for_level_base=10485760
             --filter_deletes=%s
+            --memtablerep=prefix_hash
+            --prefix_size=2
             """ % (ops_per_thread,
                    threads,
                    write_buf_size,
@@ -108,9 +110,16 @@ def main(argv):
         print("Running db_stress with pid=%d: %s\n\n"
               % (child.pid, cmd))
 
+        stop_early = False
         while time.time() < killtime:
-            time.sleep(10)
+            if child.poll() is not None:
+                print("WARNING: db_stress ended before kill: exitcode=%d\n"
+                      % child.returncode)
+                stop_early = True
+                break
+            time.sleep(1)
 
+        if not stop_early:
             if child.poll() is not None:
                 print("WARNING: db_stress ended before kill: exitcode=%d\n"
                       % child.returncode)

tools/db_crashtest2.py

@@ -107,6 +107,8 @@ def main(argv):
             --max_background_compactions=20
             --max_bytes_for_level_base=10485760
             --filter_deletes=%s
+            --memtablerep=prefix_hash
+            --prefix_size=2
             %s
             """ % (random.randint(0, 1),
                    threads,

tools/db_stress.cc

@@ -328,17 +328,17 @@ enum RepFactory StringToRepFactory(const char* ctype) {
   return kSkipList;
 }
 static enum RepFactory FLAGS_rep_factory;
-DEFINE_string(memtablerep, "skip_list", "");
+DEFINE_string(memtablerep, "prefix_hash", "");
 
 static bool ValidatePrefixSize(const char* flagname, int32_t value) {
-  if (value < 0 || value>=2000000000) {
-    fprintf(stderr, "Invalid value for --%s: %d. 0<= PrefixSize <=2000000000\n",
+  if (value < 0 || value > 8) {
+    fprintf(stderr, "Invalid value for --%s: %d. 0 <= PrefixSize <= 8\n",
             flagname, value);
     return false;
   }
   return true;
 }
-DEFINE_int32(prefix_size, 0, "Control the prefix size for HashSkipListRep");
+DEFINE_int32(prefix_size, 2, "Control the prefix size for HashSkipListRep");
 static const bool FLAGS_prefix_size_dummy =
   google::RegisterFlagValidator(&FLAGS_prefix_size, &ValidatePrefixSize);
 
@@ -931,15 +931,15 @@ class StressTest {
     return s;
   }
 
-  // Given a prefix P, this does prefix scans for "0"+P, "1"+P,..."9"+P
-  // in the same snapshot.  Each of these 10 scans returns a series of
-  // values; each series should be the same length, and it is verified
-  // for each index i that all the i'th values are of the form "0"+V,
-  // "1"+V,..."9"+V.
+  // Given a key, this does prefix scans for "0"+P, "1"+P,..."9"+P
+  // in the same snapshot where P is the first FLAGS_prefix_size - 1 bytes
+  // of the key. Each of these 10 scans returns a series of values;
+  // each series should be the same length, and it is verified for each
+  // index i that all the i'th values are of the form "0"+V, "1"+V,..."9"+V.
   // ASSUMES that MultiPut was used to put (K, V)
   Status MultiPrefixScan(ThreadState* thread,
                          const ReadOptions& readoptions,
-                         const Slice& prefix) {
+                         const Slice& key) {
     std::string prefixes[10] = {"0", "1", "2", "3", "4",
                                 "5", "6", "7", "8", "9"};
     Slice prefix_slices[10];
@@ -948,8 +948,9 @@ class StressTest {
     Iterator* iters[10];
     Status s = Status::OK();
     for (int i = 0; i < 10; i++) {
-      prefixes[i] += prefix.ToString();
-      prefix_slices[i] = prefixes[i];
+      prefixes[i] += key.ToString();
+      prefixes[i].resize(FLAGS_prefix_size);
+      prefix_slices[i] = Slice(prefixes[i]);
       readoptionscopy[i] = readoptions;
       readoptionscopy[i].prefix = &prefix_slices[i];
       readoptionscopy[i].snapshot = snapshot;
@@ -980,7 +981,7 @@ class StressTest {
       for (int i = 0; i < 10; i++) {
         if (values[i] != values[0]) {
           fprintf(stderr, "error : inconsistent values for prefix %s: %s, %s\n",
-                  prefix.ToString().c_str(), values[0].c_str(),
+                  prefixes[i].c_str(), values[0].c_str(),
                   values[i].c_str());
           // we continue after error rather than exiting so that we can
           // find more errors if any
@@ -1016,6 +1017,7 @@ class StressTest {
     const Snapshot* snapshot = db_->GetSnapshot();
     ReadOptions readoptionscopy = readoptions;
     readoptionscopy.snapshot = snapshot;
+    readoptionscopy.prefix_seek = FLAGS_prefix_size > 0;
     unique_ptr<Iterator> iter(db_->NewIterator(readoptionscopy));
 
     iter->Seek(key);
@@ -1098,8 +1100,8 @@ class StressTest {
         // keys are longs (e.g., 8 bytes), so we let prefixes be
         // everything except the last byte.  So there will be 2^8=256
         // keys per prefix.
-        Slice prefix = Slice(key.data(), key.size() - 1);
         if (!FLAGS_test_batches_snapshots) {
+          Slice prefix = Slice(key.data(), FLAGS_prefix_size);
           read_opts.prefix = &prefix;
           Iterator* iter = db_->NewIterator(read_opts);
           int count = 0;
@@ -1115,7 +1117,7 @@ class StressTest {
           }
           delete iter;
         } else {
-          MultiPrefixScan(thread, read_opts, prefix);
+          MultiPrefixScan(thread, read_opts, key);
         }
         read_opts.prefix = nullptr;
       } else if (prefixBound <= prob_op && prob_op < writeBound) {
@@ -1509,6 +1511,18 @@ int main(int argc, char** argv) {
   // max number of concurrent compactions.
   FLAGS_env->SetBackgroundThreads(FLAGS_max_background_compactions);
 
+  if (FLAGS_prefixpercent > 0 && FLAGS_prefix_size <= 0) {
+    fprintf(stderr,
+            "Error: prefixpercent is non-zero while prefix_size is "
+            "not positive!\n");
+    exit(1);
+  }
+  if (FLAGS_test_batches_snapshots && FLAGS_prefix_size <= 0) {
+    fprintf(stderr,
+            "Error: please specify prefix_size for "
+            "test_batches_snapshots test!\n");
+    exit(1);
+  }
   if ((FLAGS_readpercent + FLAGS_prefixpercent +
        FLAGS_writepercent + FLAGS_delpercent + FLAGS_iterpercent) != 100) {
       fprintf(stderr,