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// Copyright 2016 The Bazel Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "src/main/cpp/util/bazel_log_handler.h"
#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <sstream>
#include "src/main/cpp/util/file.h"
#include "src/main/cpp/util/logging.h"
namespace blaze_util {
BazelLogHandler::BazelLogHandler()
: output_stream_set_(false),
logging_deactivated_(false),
buffer_stream_(new std::stringstream()),
output_stream_(),
owned_output_stream_() {}
BazelLogHandler::~BazelLogHandler() {
if (!logging_deactivated_) {
// If SetLoggingOutputStream was never called, dump the buffer to stderr,
// otherwise, flush the stream.
if (output_stream_ != nullptr) {
output_stream_->flush();
} else if (buffer_stream_ != nullptr) {
std::cerr << buffer_stream_->rdbuf();
} else {
std::cerr << "Illegal state - neither a logfile nor a logbuffer "
<< "existed at program end." << std::endl;
}
}
}
void BazelLogHandler::HandleMessage(LogLevel level, const std::string& filename,
int line, const std::string& message) {
// Select the appropriate stream to log to.
std::ostream* log_stream;
if (logging_deactivated_) {
// Do nothing if the output stream was explicitly deactivated, unless the
// level is USER, in which case the message is meant to be user-visible
// regardless of logging settings.
if (level == LOGLEVEL_USER) {
std::cerr << message << std::endl;
}
return;
} else if (output_stream_ == nullptr) {
log_stream = buffer_stream_.get();
} else {
log_stream = output_stream_;
}
(*log_stream) << "[bazel " << LogLevelName(level) << " " << filename << ":"
<< line << "] " << message << std::endl;
// If we have a fatal message, we should abort and leave a stack trace -
// normal exit behavior will be lost, so print this log message out to
// stderr and avoid loosing the information.
if (level == LOGLEVEL_FATAL) {
std::cerr << "[bazel " << LogLevelName(level) << " " << filename << ":"
<< line << "] " << message << std::endl;
std::abort();
}
}
void BazelLogHandler::SetOutputStreamToStderr() {
// Disallow second calls to this, we only intend to support setting the output
// once, otherwise the buffering will not work as intended and the log will be
// fragmented.
BAZEL_CHECK(!output_stream_set_) << "Tried to set log output a second time";
output_stream_set_ = true;
FlushBufferToNewStreamAndSet(&std::cerr);
}
void BazelLogHandler::SetOutputStream(
std::unique_ptr<std::ostream> new_output_stream) {
// Disallow second calls to this, we only intend to support setting the output
// once, otherwise the buffering will not work as intended and the log will be
// fragmented.
BAZEL_CHECK(!output_stream_set_) << "Tried to set log output a second time";
output_stream_set_ = true;
if (new_output_stream == nullptr) {
logging_deactivated_ = true;
buffer_stream_ = nullptr;
return;
}
owned_output_stream_ = std::move(new_output_stream);
FlushBufferToNewStreamAndSet(owned_output_stream_.get());
}
void BazelLogHandler::FlushBufferToNewStreamAndSet(
std::ostream* new_output_stream) {
// Flush the buffer to the new stream, and print new log lines to it.
output_stream_ = new_output_stream;
if (output_stream_->fail()) {
// If opening the stream failed, continue buffering and have the logs
// dump to stderr at shutdown.
output_stream_ = nullptr;
BAZEL_LOG(ERROR) << "Provided stream failed.";
} else {
// Transfer the contents of the buffer to the new stream, then remove the
// buffer.
(*output_stream_) << buffer_stream_->str();
buffer_stream_ = nullptr;
output_stream_->flush();
}
}
} // namespace blaze_util
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