rocksdb/util/stderr_logger.h
Neil Ramaswamy 4835c11cce Add native logger support to RocksJava (#12213)
Summary:
## Overview

In this PR, we introduce support for setting the RocksDB native logger through Java. As mentioned in the discussion on the [Google Group discussion](https://groups.google.com/g/rocksdb/c/xYmbEs4sqRM/m/e73E4whJAQAJ), this work is primarily motivated by the  JDK 17 [performance regression in JNI thread attach/detach calls](https://bugs.openjdk.org/browse/JDK-8314859): the only existing RocksJava logging configuration call, `setLogger`, invokes the provided logger over the JNI.

## Changes

Specifically, these changes add support for the `devnull` and `stderr` native loggers. For the `stderr` logger, we add the ability to prefix every log with a `logPrefix`, so that it becomes possible know which database a particular log is coming from (if multiple databases are in use). The  API looks like the following:

```java
Options opts = new Options();

NativeLogger stderrNativeLogger = NativeLogger.newStderrLogger(
  InfoLogLevel.DEBUG_LEVEL, "[my prefix here]");
options.setLogger(stderrNativeLogger);

try (final RocksDB db = RocksDB.open(options, ...))  {...}

// Cleanup
stderrNativeLogger.close()
opts.close();
```

Note that the API to set the logger is the same, via `Options::setLogger` (or `DBOptions::setLogger`). However, it will set the RocksDB logger to be native when  the provided logger is an instance of `NativeLogger`.

## Testing

Two tests have been added in `NativeLoggerTest.java`. The first test creates both the `devnull` and `stderr` loggers, and sets them on the associated `Options`. However, to avoid polluting the testing output with logs from `stderr`, only the `devnull` logger is actually used in the test. The second test does the same logic, but for `DBOptions`.

It is possible to manually verify the `stderr` logger by modifying the tests slightly, and observing that the console indeed gets cluttered with logs from `stderr`.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/12213

Reviewed By: cbi42

Differential Revision: D52772306

Pulled By: ajkr

fbshipit-source-id: 4026895f78f9cc250daf6bfa57427957e2d8b053
2024-01-17 17:51:36 -08:00

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1.2 KiB
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// Copyright (c) Meta Platforms, Inc. and affiliates.
//
// 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).
#pragma once
#include <stdarg.h>
#include <stdio.h>
#include "rocksdb/env.h"
namespace ROCKSDB_NAMESPACE {
// Prints logs to stderr for faster debugging
class StderrLogger : public Logger {
public:
explicit StderrLogger(const InfoLogLevel log_level = InfoLogLevel::INFO_LEVEL)
: Logger(log_level), log_prefix(nullptr) {}
explicit StderrLogger(const InfoLogLevel log_level, const std::string prefix)
: Logger(log_level),
log_prefix(strdup(prefix.c_str())),
log_prefix_len(strlen(log_prefix)) {}
~StderrLogger() override;
// Brings overloaded Logv()s into scope so they're not hidden when we override
// a subset of them.
using Logger::Logv;
virtual void Logv(const char* format, va_list ap) override;
private:
// This prefix will be appended after the time/thread info of every log
const char* log_prefix;
// The length of the log_prefix
size_t log_prefix_len;
};
} // namespace ROCKSDB_NAMESPACE