Squashed 'src/rocksdb/' content from commit 224932d

git-subtree-dir: src/rocksdb
git-subtree-split: 224932d4d0b561712107d747c662df181c39644d

util/log_buffer.h

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+// Copyright (c) 2014, Facebook, Inc. All rights reserved.
+// This source code is licensed under the BSD-style license found in the
+// LICENSE file in the root directory of this source tree. An additional grant
+// of patent rights can be found in the PATENTS file in the same directory.
+
+#pragma once
+
+#include "rocksdb/env.h"
+#include "util/arena.h"
+#include "util/autovector.h"
+#include <ctime>
+
+namespace rocksdb {
+
+class Logger;
+
+// A class to buffer info log entries and flush them in the end.
+class LogBuffer {
+ public:
+  // log_level: the log level for all the logs
+  // info_log:  logger to write the logs to
+  LogBuffer(const InfoLogLevel log_level, Logger* info_log);
+
+  // Add a log entry to the buffer.
+  void AddLogToBuffer(const char* format, va_list ap);
+
+  size_t IsEmpty() const { return logs_.empty(); }
+
+  // Flush all buffered log to the info log.
+  void FlushBufferToLog();
+
+ private:
+  // One log entry with its timestamp
+  struct BufferedLog {
+    struct timeval now_tv;  // Timestamp of the log
+    char message[1];        // Beginning of log message
+  };
+
+  const InfoLogLevel log_level_;
+  Logger* info_log_;
+  Arena arena_;
+  autovector<BufferedLog*> logs_;
+};
+
+// Add log to the LogBuffer for a delayed info logging. It can be used when
+// we want to add some logs inside a mutex.
+extern void LogToBuffer(LogBuffer* log_buffer, const char* format, ...);
+
+}  // namespace rocksdb