1 files changed, 316 insertions, 0 deletions

diff --git a/src/rocksdb/utilities/trace/replayer_impl.cc b/src/rocksdb/utilities/trace/replayer_impl.cc
new file mode 100644
index 000000000..31023f1a2
--- /dev/null
+++ b/src/rocksdb/utilities/trace/replayer_impl.cc
@@ -0,0 +1,316 @@
+//  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).
+
+#ifndef ROCKSDB_LITE
+
+#include "utilities/trace/replayer_impl.h"
+
+#include <cmath>
+#include <thread>
+
+#include "rocksdb/options.h"
+#include "rocksdb/slice.h"
+#include "rocksdb/system_clock.h"
+#include "util/threadpool_imp.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+ReplayerImpl::ReplayerImpl(DB* db,
+                           const std::vector<ColumnFamilyHandle*>& handles,
+                           std::unique_ptr<TraceReader>&& reader)
+    : Replayer(),
+      trace_reader_(std::move(reader)),
+      prepared_(false),
+      trace_end_(false),
+      header_ts_(0),
+      exec_handler_(TraceRecord::NewExecutionHandler(db, handles)),
+      env_(db->GetEnv()),
+      trace_file_version_(-1) {}
+
+ReplayerImpl::~ReplayerImpl() {
+  exec_handler_.reset();
+  trace_reader_.reset();
+}
+
+Status ReplayerImpl::Prepare() {
+  Trace header;
+  int db_version;
+  Status s = ReadHeader(&header);
+  if (!s.ok()) {
+    return s;
+  }
+  s = TracerHelper::ParseTraceHeader(header, &trace_file_version_, &db_version);
+  if (!s.ok()) {
+    return s;
+  }
+  header_ts_ = header.ts;
+  prepared_ = true;
+  trace_end_ = false;
+  return Status::OK();
+}
+
+Status ReplayerImpl::Next(std::unique_ptr<TraceRecord>* record) {
+  if (!prepared_) {
+    return Status::Incomplete("Not prepared!");
+  }
+  if (trace_end_) {
+    return Status::Incomplete("Trace end.");
+  }
+
+  Trace trace;
+  Status s = ReadTrace(&trace);  // ReadTrace is atomic
+  // Reached the trace end.
+  if (s.ok() && trace.type == kTraceEnd) {
+    trace_end_ = true;
+    return Status::Incomplete("Trace end.");
+  }
+  if (!s.ok() || record == nullptr) {
+    return s;
+  }
+
+  return TracerHelper::DecodeTraceRecord(&trace, trace_file_version_, record);
+}
+
+Status ReplayerImpl::Execute(const std::unique_ptr<TraceRecord>& record,
+                             std::unique_ptr<TraceRecordResult>* result) {
+  return record->Accept(exec_handler_.get(), result);
+}
+
+Status ReplayerImpl::Replay(
+    const ReplayOptions& options,
+    const std::function<void(Status, std::unique_ptr<TraceRecordResult>&&)>&
+        result_callback) {
+  if (options.fast_forward <= 0.0) {
+    return Status::InvalidArgument("Wrong fast forward speed!");
+  }
+
+  if (!prepared_) {
+    return Status::Incomplete("Not prepared!");
+  }
+  if (trace_end_) {
+    return Status::Incomplete("Trace end.");
+  }
+
+  Status s = Status::OK();
+
+  if (options.num_threads <= 1) {
+    // num_threads == 0 or num_threads == 1 uses single thread.
+    std::chrono::system_clock::time_point replay_epoch =
+        std::chrono::system_clock::now();
+
+    while (s.ok()) {
+      Trace trace;
+      s = ReadTrace(&trace);
+      // If already at trace end, ReadTrace should return Status::Incomplete().
+      if (!s.ok()) {
+        break;
+      }
+
+      // No need to sleep before breaking the loop if at the trace end.
+      if (trace.type == kTraceEnd) {
+        trace_end_ = true;
+        s = Status::Incomplete("Trace end.");
+        break;
+      }
+
+      // In single-threaded replay, decode first then sleep.
+      std::unique_ptr<TraceRecord> record;
+      s = TracerHelper::DecodeTraceRecord(&trace, trace_file_version_, &record);
+      if (!s.ok() && !s.IsNotSupported()) {
+        break;
+      }
+
+      std::chrono::system_clock::time_point sleep_to =
+          replay_epoch +
+          std::chrono::microseconds(static_cast<uint64_t>(std::llround(
+              1.0 * (trace.ts - header_ts_) / options.fast_forward)));
+      if (sleep_to > std::chrono::system_clock::now()) {
+        std::this_thread::sleep_until(sleep_to);
+      }
+
+      // Skip unsupported traces, stop for other errors.
+      if (s.IsNotSupported()) {
+        if (result_callback != nullptr) {
+          result_callback(s, nullptr);
+        }
+        s = Status::OK();
+        continue;
+      }
+
+      if (result_callback == nullptr) {
+        s = Execute(record, nullptr);
+      } else {
+        std::unique_ptr<TraceRecordResult> res;
+        s = Execute(record, &res);
+        result_callback(s, std::move(res));
+      }
+    }
+  } else {
+    // Multi-threaded replay.
+    ThreadPoolImpl thread_pool;
+    thread_pool.SetHostEnv(env_);
+    thread_pool.SetBackgroundThreads(static_cast<int>(options.num_threads));
+
+    std::mutex mtx;
+    // Background decoding and execution status.
+    Status bg_s = Status::OK();
+    uint64_t last_err_ts = static_cast<uint64_t>(-1);
+    // Callback function used in background work to update bg_s for the ealiest
+    // TraceRecord which has execution error. This is different from the
+    // timestamp of the first execution error (either start or end timestamp).
+    //
+    // Suppose TraceRecord R1, R2, with timestamps T1 < T2. Their execution
+    // timestamps are T1_start, T1_end, T2_start, T2_end.
+    // Single-thread: there must be T1_start < T1_end < T2_start < T2_end.
+    // Multi-thread: T1_start < T2_start may not be enforced. Orders of them are
+    // totally unknown.
+    // In order to report the same `first` error in both single-thread and
+    // multi-thread replay, we can only rely on the TraceRecords' timestamps,
+    // rather than their executin timestamps. Although in single-thread replay,
+    // the first error is also the last error, while in multi-thread replay, the
+    // first error may not be the first error in execution, and it may not be
+    // the last error in exeution as well.
+    auto error_cb = [&mtx, &bg_s, &last_err_ts](Status err, uint64_t err_ts) {
+      std::lock_guard<std::mutex> gd(mtx);
+      // Only record the first error.
+      if (!err.ok() && !err.IsNotSupported() && err_ts < last_err_ts) {
+        bg_s = err;
+        last_err_ts = err_ts;
+      }
+    };
+
+    std::chrono::system_clock::time_point replay_epoch =
+        std::chrono::system_clock::now();
+
+    while (bg_s.ok() && s.ok()) {
+      Trace trace;
+      s = ReadTrace(&trace);
+      // If already at trace end, ReadTrace should return Status::Incomplete().
+      if (!s.ok()) {
+        break;
+      }
+
+      TraceType trace_type = trace.type;
+
+      // No need to sleep before breaking the loop if at the trace end.
+      if (trace_type == kTraceEnd) {
+        trace_end_ = true;
+        s = Status::Incomplete("Trace end.");
+        break;
+      }
+
+      // In multi-threaded replay, sleep first then start decoding and
+      // execution in a thread.
+      std::chrono::system_clock::time_point sleep_to =
+          replay_epoch +
+          std::chrono::microseconds(static_cast<uint64_t>(std::llround(
+              1.0 * (trace.ts - header_ts_) / options.fast_forward)));
+      if (sleep_to > std::chrono::system_clock::now()) {
+        std::this_thread::sleep_until(sleep_to);
+      }
+
+      if (trace_type == kTraceWrite || trace_type == kTraceGet ||
+          trace_type == kTraceIteratorSeek ||
+          trace_type == kTraceIteratorSeekForPrev ||
+          trace_type == kTraceMultiGet) {
+        std::unique_ptr<ReplayerWorkerArg> ra(new ReplayerWorkerArg);
+        ra->trace_entry = std::move(trace);
+        ra->handler = exec_handler_.get();
+        ra->trace_file_version = trace_file_version_;
+        ra->error_cb = error_cb;
+        ra->result_cb = result_callback;
+        thread_pool.Schedule(&ReplayerImpl::BackgroundWork, ra.release(),
+                             nullptr, nullptr);
+      } else {
+        // Skip unsupported traces.
+        if (result_callback != nullptr) {
+          result_callback(Status::NotSupported("Unsupported trace type."),
+                          nullptr);
+        }
+      }
+    }
+
+    thread_pool.WaitForJobsAndJoinAllThreads();
+    if (!bg_s.ok()) {
+      s = bg_s;
+    }
+  }
+
+  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.
+    trace_end_ = true;
+    return Status::OK();
+  }
+  return s;
+}
+
+uint64_t ReplayerImpl::GetHeaderTimestamp() const { return header_ts_; }
+
+Status ReplayerImpl::ReadHeader(Trace* header) {
+  assert(header != nullptr);
+  Status s = trace_reader_->Reset();
+  if (!s.ok()) {
+    return s;
+  }
+  std::string encoded_trace;
+  // Read the trace head
+  s = trace_reader_->Read(&encoded_trace);
+  if (!s.ok()) {
+    return s;
+  }
+
+  return TracerHelper::DecodeHeader(encoded_trace, header);
+}
+
+Status ReplayerImpl::ReadTrace(Trace* trace) {
+  assert(trace != nullptr);
+  std::string encoded_trace;
+  // We don't know if TraceReader is implemented thread-safe, so we protect the
+  // reading trace part with a mutex. The decoding part does not need to be
+  // protected since it's local.
+  {
+    std::lock_guard<std::mutex> guard(mutex_);
+    Status s = trace_reader_->Read(&encoded_trace);
+    if (!s.ok()) {
+      return s;
+    }
+  }
+  return TracerHelper::DecodeTrace(encoded_trace, trace);
+}
+
+void ReplayerImpl::BackgroundWork(void* arg) {
+  std::unique_ptr<ReplayerWorkerArg> ra(
+      reinterpret_cast<ReplayerWorkerArg*>(arg));
+  assert(ra != nullptr);
+
+  std::unique_ptr<TraceRecord> record;
+  Status s = TracerHelper::DecodeTraceRecord(&(ra->trace_entry),
+                                             ra->trace_file_version, &record);
+  if (!s.ok()) {
+    // Stop the replay
+    if (ra->error_cb != nullptr) {
+      ra->error_cb(s, ra->trace_entry.ts);
+    }
+    // Report the result
+    if (ra->result_cb != nullptr) {
+      ra->result_cb(s, nullptr);
+    }
+    return;
+  }
+
+  if (ra->result_cb == nullptr) {
+    s = record->Accept(ra->handler, nullptr);
+  } else {
+    std::unique_ptr<TraceRecordResult> res;
+    s = record->Accept(ra->handler, &res);
+    ra->result_cb(s, std::move(res));
+  }
+  record.reset();
+}
+
+}  // namespace ROCKSDB_NAMESPACE
+#endif  // ROCKSDB_LITE