1 files changed, 300 insertions, 0 deletions
diff --git a/src/rocksdb/util/trace_replay.cc b/src/rocksdb/util/trace_replay.cc
new file mode 100644
index 00000000..28160b29
--- /dev/null
+++ b/src/rocksdb/util/trace_replay.cc
@@ -0,0 +1,300 @@
+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+
+#include "util/trace_replay.h"
+
+#include <chrono>
+#include <sstream>
+#include <thread>
+#include "db/db_impl.h"
+#include "rocksdb/slice.h"
+#include "rocksdb/write_batch.h"
+#include "util/coding.h"
+#include "util/string_util.h"
+
+namespace rocksdb {
+
+const std::string kTraceMagic = "feedcafedeadbeef";
+
+namespace {
+void EncodeCFAndKey(std::string* dst, uint32_t cf_id, const Slice& key) {
+  PutFixed32(dst, cf_id);
+  PutLengthPrefixedSlice(dst, key);
+}
+
+void DecodeCFAndKey(std::string& buffer, uint32_t* cf_id, Slice* key) {
+  Slice buf(buffer);
+  GetFixed32(&buf, cf_id);
+  GetLengthPrefixedSlice(&buf, key);
+}
+}  // namespace
+
+Tracer::Tracer(Env* env, const TraceOptions& trace_options,
+               std::unique_ptr<TraceWriter>&& trace_writer)
+    : env_(env),
+      trace_options_(trace_options),
+      trace_writer_(std::move(trace_writer)),
+      trace_request_count_ (0) {
+  WriteHeader();
+}
+
+Tracer::~Tracer() { trace_writer_.reset(); }
+
+Status Tracer::Write(WriteBatch* write_batch) {
+  TraceType trace_type = kTraceWrite;
+  if (ShouldSkipTrace(trace_type)) {
+    return Status::OK();
+  }
+  Trace trace;
+  trace.ts = env_->NowMicros();
+  trace.type = trace_type;
+  trace.payload = write_batch->Data();
+  return WriteTrace(trace);
+}
+
+Status Tracer::Get(ColumnFamilyHandle* column_family, const Slice& key) {
+  TraceType trace_type = kTraceGet;
+  if (ShouldSkipTrace(trace_type)) {
+    return Status::OK();
+  }
+  Trace trace;
+  trace.ts = env_->NowMicros();
+  trace.type = trace_type;
+  EncodeCFAndKey(&trace.payload, column_family->GetID(), key);
+  return WriteTrace(trace);
+}
+
+Status Tracer::IteratorSeek(const uint32_t& cf_id, const Slice& key) {
+  TraceType trace_type = kTraceIteratorSeek;
+  if (ShouldSkipTrace(trace_type)) {
+    return Status::OK();
+  }
+  Trace trace;
+  trace.ts = env_->NowMicros();
+  trace.type = trace_type;
+  EncodeCFAndKey(&trace.payload, cf_id, key);
+  return WriteTrace(trace);
+}
+
+Status Tracer::IteratorSeekForPrev(const uint32_t& cf_id, const Slice& key) {
+  TraceType trace_type = kTraceIteratorSeekForPrev;
+  if (ShouldSkipTrace(trace_type)) {
+    return Status::OK();
+  }
+  Trace trace;
+  trace.ts = env_->NowMicros();
+  trace.type = trace_type;
+  EncodeCFAndKey(&trace.payload, cf_id, key);
+  return WriteTrace(trace);
+}
+
+bool Tracer::ShouldSkipTrace(const TraceType& trace_type) {
+  if (IsTraceFileOverMax()) {
+    return true;
+  }
+  if ((trace_options_.filter & kTraceFilterGet
+    && trace_type == kTraceGet)
+   || (trace_options_.filter & kTraceFilterWrite
+    && trace_type == kTraceWrite)) {
+    return true;
+  }
+  ++trace_request_count_;
+  if (trace_request_count_ < trace_options_.sampling_frequency) {
+    return true;
+  }
+  trace_request_count_ = 0;
+  return false;
+}
+
+bool Tracer::IsTraceFileOverMax() {
+  uint64_t trace_file_size = trace_writer_->GetFileSize();
+  return (trace_file_size > trace_options_.max_trace_file_size);
+}
+
+Status Tracer::WriteHeader() {
+  std::ostringstream s;
+  s << kTraceMagic << "\t"
+    << "Trace Version: 0.1\t"
+    << "RocksDB Version: " << kMajorVersion << "." << kMinorVersion << "\t"
+    << "Format: Timestamp OpType Payload\n";
+  std::string header(s.str());
+
+  Trace trace;
+  trace.ts = env_->NowMicros();
+  trace.type = kTraceBegin;
+  trace.payload = header;
+  return WriteTrace(trace);
+}
+
+Status Tracer::WriteFooter() {
+  Trace trace;
+  trace.ts = env_->NowMicros();
+  trace.type = kTraceEnd;
+  trace.payload = "";
+  return WriteTrace(trace);
+}
+
+Status Tracer::WriteTrace(const Trace& trace) {
+  std::string encoded_trace;
+  PutFixed64(&encoded_trace, trace.ts);
+  encoded_trace.push_back(trace.type);
+  PutFixed32(&encoded_trace, static_cast<uint32_t>(trace.payload.size()));
+  encoded_trace.append(trace.payload);
+  return trace_writer_->Write(Slice(encoded_trace));
+}
+
+Status Tracer::Close() { return WriteFooter(); }
+
+Replayer::Replayer(DB* db, const std::vector<ColumnFamilyHandle*>& handles,
+                   std::unique_ptr<TraceReader>&& reader)
+    : trace_reader_(std::move(reader)) {
+  assert(db != nullptr);
+  db_ = static_cast<DBImpl*>(db->GetRootDB());
+  for (ColumnFamilyHandle* cfh : handles) {
+    cf_map_[cfh->GetID()] = cfh;
+  }
+}
+
+Replayer::~Replayer() { trace_reader_.reset(); }
+
+Status Replayer::Replay() {
+  Status s;
+  Trace header;
+  s = ReadHeader(&header);
+  if (!s.ok()) {
+    return s;
+  }
+
+  std::chrono::system_clock::time_point replay_epoch =
+      std::chrono::system_clock::now();
+  WriteOptions woptions;
+  ReadOptions roptions;
+  Trace trace;
+  uint64_t ops = 0;
+  Iterator* single_iter = nullptr;
+  while (s.ok()) {
+    trace.reset();
+    s = ReadTrace(&trace);
+    if (!s.ok()) {
+      break;
+    }
+
+    std::this_thread::sleep_until(
+        replay_epoch + std::chrono::microseconds(trace.ts - header.ts));
+    if (trace.type == kTraceWrite) {
+      WriteBatch batch(trace.payload);
+      db_->Write(woptions, &batch);
+      ops++;
+    } else if (trace.type == kTraceGet) {
+      uint32_t cf_id = 0;
+      Slice key;
+      DecodeCFAndKey(trace.payload, &cf_id, &key);
+      if (cf_id > 0 && cf_map_.find(cf_id) == cf_map_.end()) {
+        return Status::Corruption("Invalid Column Family ID.");
+      }
+
+      std::string value;
+      if (cf_id == 0) {
+        db_->Get(roptions, key, &value);
+      } else {
+        db_->Get(roptions, cf_map_[cf_id], key, &value);
+      }
+      ops++;
+    } else if (trace.type == kTraceIteratorSeek) {
+      uint32_t cf_id = 0;
+      Slice key;
+      DecodeCFAndKey(trace.payload, &cf_id, &key);
+      if (cf_id > 0 && cf_map_.find(cf_id) == cf_map_.end()) {
+        return Status::Corruption("Invalid Column Family ID.");
+      }
+
+      if (cf_id == 0) {
+        single_iter = db_->NewIterator(roptions);
+      } else {
+        single_iter = db_->NewIterator(roptions, cf_map_[cf_id]);
+      }
+      single_iter->Seek(key);
+      ops++;
+      delete single_iter;
+    } else if (trace.type == kTraceIteratorSeekForPrev) {
+      // Currently, only support to call the Seek()
+      uint32_t cf_id = 0;
+      Slice key;
+      DecodeCFAndKey(trace.payload, &cf_id, &key);
+      if (cf_id > 0 && cf_map_.find(cf_id) == cf_map_.end()) {
+        return Status::Corruption("Invalid Column Family ID.");
+      }
+
+      if (cf_id == 0) {
+        single_iter = db_->NewIterator(roptions);
+      } else {
+        single_iter = db_->NewIterator(roptions, cf_map_[cf_id]);
+      }
+      single_iter->SeekForPrev(key);
+      ops++;
+      delete single_iter;
+    } else if (trace.type == kTraceEnd) {
+      // Do nothing for now.
+      // TODO: Add some validations later.
+      break;
+    }
+  }
+
+  if (s.IsIncomplete()) {
+    // Reaching eof returns Incomplete status at the moment.
+    // Could happen when killing a process without calling EndTrace() API.
+    // TODO: Add better error handling.
+    return Status::OK();
+  }
+  return s;
+}
+
+Status Replayer::ReadHeader(Trace* header) {
+  assert(header != nullptr);
+  Status s = ReadTrace(header);
+  if (!s.ok()) {
+    return s;
+  }
+  if (header->type != kTraceBegin) {
+    return Status::Corruption("Corrupted trace file. Incorrect header.");
+  }
+  if (header->payload.substr(0, kTraceMagic.length()) != kTraceMagic) {
+    return Status::Corruption("Corrupted trace file. Incorrect magic.");
+  }
+
+  return s;
+}
+
+Status Replayer::ReadFooter(Trace* footer) {
+  assert(footer != nullptr);
+  Status s = ReadTrace(footer);
+  if (!s.ok()) {
+    return s;
+  }
+  if (footer->type != kTraceEnd) {
+    return Status::Corruption("Corrupted trace file. Incorrect footer.");
+  }
+
+  // TODO: Add more validations later
+  return s;
+}
+
+Status Replayer::ReadTrace(Trace* trace) {
+  assert(trace != nullptr);
+  std::string encoded_trace;
+  Status s = trace_reader_->Read(&encoded_trace);
+  if (!s.ok()) {
+    return s;
+  }
+
+  Slice enc_slice = Slice(encoded_trace);
+  GetFixed64(&enc_slice, &trace->ts);
+  trace->type = static_cast<TraceType>(enc_slice[0]);
+  enc_slice.remove_prefix(kTraceTypeSize + kTracePayloadLengthSize);
+  trace->payload = enc_slice.ToString();
+  return s;
+}
+
+}  // namespace rocksdb