111 lines
3.5 KiB
C++
111 lines
3.5 KiB
C++
/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <folly/logging/AsyncFileWriter.h>
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#include <folly/Exception.h>
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#include <folly/FileUtil.h>
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#include <folly/logging/LoggerDB.h>
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namespace folly {
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AsyncFileWriter::AsyncFileWriter(StringPiece path)
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: AsyncFileWriter{File{path.str(), O_WRONLY | O_APPEND | O_CREAT}} {}
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AsyncFileWriter::AsyncFileWriter(folly::File&& file) : file_{std::move(file)} {}
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AsyncFileWriter::~AsyncFileWriter() {
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cleanup();
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}
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bool AsyncFileWriter::ttyOutput() const {
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return isatty(file_.fd());
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}
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void AsyncFileWriter::writeToFile(
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const std::vector<std::string>& ioQueue, size_t numDiscarded) {
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#ifndef _WIN32
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// kNumIovecs controls the maximum number of strings we write at once in a
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// single writev() call.
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constexpr int kNumIovecs = 64;
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std::array<iovec, kNumIovecs> iovecs;
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#endif // !_WIN32
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size_t idx = 0;
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while (idx < ioQueue.size()) {
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#ifndef _WIN32
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// On POSIX platforms use writev() to minimize the number of system calls
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// we use to write the data.
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int numIovecs = 0;
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while (numIovecs < kNumIovecs && idx < ioQueue.size()) {
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const auto& str = ioQueue[idx];
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iovecs[numIovecs].iov_base = const_cast<char*>(str.data());
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iovecs[numIovecs].iov_len = str.size();
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++numIovecs;
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++idx;
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}
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auto ret = folly::writevFull(file_.fd(), iovecs.data(), numIovecs);
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folly::checkUnixError(ret, "writevFull() failed");
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#else // _WIN32
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// On Windows folly's writevFull() function is just a wrapper that calls
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// write() multiple times. Go ahead and do that ourselves here, since there
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// is no point constructing the iovec data structure.
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auto ret =
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folly::writeFull(file_.fd(), ioQueue[idx].data(), ioQueue[idx].size());
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folly::checkUnixError(ret, "writeFull() failed");
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CHECK_EQ(ret, ioQueue[idx].size());
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++idx;
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#endif // _WIN32
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}
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if (numDiscarded > 0) {
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auto msg = getNumDiscardedMsg(numDiscarded);
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if (!msg.empty()) {
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auto ret = folly::writeFull(file_.fd(), msg.data(), msg.size());
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// We currently ignore errors from writeFull() here.
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// There's not much we can really do.
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(void)ret;
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}
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}
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}
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void AsyncFileWriter::performIO(
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const std::vector<std::string>& ioQueue, size_t numDiscarded) {
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try {
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writeToFile(ioQueue, numDiscarded);
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} catch (const std::exception& ex) {
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LoggerDB::internalWarning(
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__FILE__,
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__LINE__,
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"error writing to log file ",
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file_.fd(),
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" in AsyncFileWriter: ",
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folly::exceptionStr(ex));
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}
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}
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std::string AsyncFileWriter::getNumDiscardedMsg(size_t numDiscarded) {
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// We may want to make this customizable in the future (e.g., to allow it to
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// conform to the LogFormatter style being used).
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// For now just return a simple fixed message.
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return folly::to<std::string>(
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numDiscarded,
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" log messages discarded: logging faster than we can write\n");
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}
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} // namespace folly
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