Forge current file for checkpoint

Summary:
This fixes a similar issue as D54711: "CURRENT" file can mutate between
GetLiveFiles() and copy to the tmp directory, in which case it would reference
the wrong manifest filename. To fix this, I forge the "CURRENT" file such that
it simply contains the filename for the manifest returned by GetLiveFiles().

- Changed CreateCheckpoint() to forge current file
- Added CreateFile() utility function
- Added test case that rolls manifest during checkpoint creation

Test Plan:
  $ ./checkpoint_test

Reviewers: sdong, IslamAbdelRahman

Reviewed By: IslamAbdelRahman

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D55065
main
Andrew Kryczka 9 years ago
parent 33d568611d
commit 72224104d3
  1. 16
      util/file_util.cc
  2. 3
      util/file_util.h
  3. 19
      utilities/checkpoint/checkpoint.cc
  4. 44
      utilities/checkpoint/checkpoint_test.cc

@ -66,6 +66,22 @@ Status CopyFile(Env* env, const std::string& source,
return Status::OK();
}
// Utility function to create a file with the provided contents
Status CreateFile(Env* env, const std::string& destination,
const std::string& contents) {
const EnvOptions soptions;
Status s;
unique_ptr<WritableFileWriter> dest_writer;
unique_ptr<WritableFile> destfile;
s = env->NewWritableFile(destination, &destfile, soptions);
if (!s.ok()) {
return s;
}
dest_writer.reset(new WritableFileWriter(std::move(destfile), soptions));
return dest_writer->Append(Slice(contents));
}
Status DeleteSSTFile(const DBOptions* db_options, const std::string& fname,
uint32_t path_id) {
// TODO(tec): support sst_file_manager for multiple path_ids

@ -16,6 +16,9 @@ namespace rocksdb {
extern Status CopyFile(Env* env, const std::string& source,
const std::string& destination, uint64_t size = 0);
extern Status CreateFile(Env* env, const std::string& destination,
const std::string& contents);
extern Status DeleteSSTFile(const DBOptions* db_options,
const std::string& fname, uint32_t path_id);

@ -24,6 +24,7 @@
#include "rocksdb/env.h"
#include "rocksdb/transaction_log.h"
#include "util/file_util.h"
#include "util/sync_point.h"
#include "port/port.h"
namespace rocksdb {
@ -76,7 +77,9 @@ Status CheckpointImpl::CreateCheckpoint(const std::string& checkpoint_dir) {
s = db_->DisableFileDeletions();
if (s.ok()) {
// this will return live_files prefixed with "/"
s = db_->GetLiveFiles(live_files, &manifest_file_size, true);
s = db_->GetLiveFiles(live_files, &manifest_file_size);
TEST_SYNC_POINT("CheckpointImpl::CreateCheckpoint:SavedLiveFiles1");
TEST_SYNC_POINT("CheckpointImpl::CreateCheckpoint:SavedLiveFiles2");
}
// if we have more than one column family, we need to also get WAL files
if (s.ok()) {
@ -98,6 +101,7 @@ Status CheckpointImpl::CreateCheckpoint(const std::string& checkpoint_dir) {
s = db_->GetEnv()->CreateDir(full_private_path);
// copy/hard link live_files
std::string manifest_fname, current_fname;
for (size_t i = 0; s.ok() && i < live_files.size(); ++i) {
uint64_t number;
FileType type;
@ -110,6 +114,15 @@ Status CheckpointImpl::CreateCheckpoint(const std::string& checkpoint_dir) {
assert(type == kTableFile || type == kDescriptorFile ||
type == kCurrentFile);
assert(live_files[i].size() > 0 && live_files[i][0] == '/');
if (type == kCurrentFile) {
// We will craft the current file manually to ensure it's consistent with
// the manifest number. This is necessary because current's file contents
// can change during checkpoint creation.
current_fname = live_files[i];
continue;
} else if (type == kDescriptorFile) {
manifest_fname = live_files[i];
}
std::string src_fname = live_files[i];
// rules:
@ -132,6 +145,10 @@ Status CheckpointImpl::CreateCheckpoint(const std::string& checkpoint_dir) {
(type == kDescriptorFile) ? manifest_file_size : 0);
}
}
if (s.ok() && !current_fname.empty() && !manifest_fname.empty()) {
s = CreateFile(db_->GetEnv(), full_private_path + current_fname,
manifest_fname.substr(1) + "\n");
}
Log(db_->GetOptions().info_log, "Number of log files %" ROCKSDB_PRIszt,
live_wal_files.size());

@ -346,6 +346,50 @@ TEST_F(DBTest, CheckpointCF) {
ASSERT_OK(DestroyDB(snapshot_name, options));
}
TEST_F(DBTest, CurrentFileModifiedWhileCheckpointing) {
const std::string kSnapshotName = test::TmpDir(env_) + "/snapshot";
ASSERT_OK(DestroyDB(kSnapshotName, CurrentOptions()));
env_->DeleteDir(kSnapshotName);
Options options = CurrentOptions();
options.max_manifest_file_size = 0; // always rollover manifest for file add
Reopen(options);
rocksdb::SyncPoint::GetInstance()->LoadDependency(
{// Get past the flush in the checkpoint thread before adding any keys to
// the db so the checkpoint thread won't hit the WriteManifest
// syncpoints.
{"DBImpl::GetLiveFiles:1",
"DBTest::CurrentFileModifiedWhileCheckpointing:PrePut"},
// Roll the manifest during checkpointing right after live files are
// snapshotted.
{"CheckpointImpl::CreateCheckpoint:SavedLiveFiles1",
"VersionSet::LogAndApply:WriteManifest"},
{"VersionSet::LogAndApply:WriteManifestDone",
"CheckpointImpl::CreateCheckpoint:SavedLiveFiles2"}});
rocksdb::SyncPoint::GetInstance()->EnableProcessing();
std::thread t([&]() {
Checkpoint* checkpoint;
ASSERT_OK(Checkpoint::Create(db_, &checkpoint));
ASSERT_OK(checkpoint->CreateCheckpoint(kSnapshotName));
delete checkpoint;
});
TEST_SYNC_POINT("DBTest::CurrentFileModifiedWhileCheckpointing:PrePut");
ASSERT_OK(Put("Default", "Default1"));
ASSERT_OK(Flush());
t.join();
rocksdb::SyncPoint::GetInstance()->DisableProcessing();
DB* snapshotDB;
// Successful Open() implies that CURRENT pointed to the manifest in the
// checkpoint.
ASSERT_OK(DB::Open(options, kSnapshotName, &snapshotDB));
delete snapshotDB;
snapshotDB = nullptr;
}
} // namespace rocksdb
int main(int argc, char** argv) {

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