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Diffstat (limited to 'third_party/abseil_cpp/absl/base/internal/raw_logging.h')
| -rw-r--r-- | third_party/abseil_cpp/absl/base/internal/raw_logging.h | 183 |
1 files changed, 183 insertions, 0 deletions
diff --git a/third_party/abseil_cpp/absl/base/internal/raw_logging.h b/third_party/abseil_cpp/absl/base/internal/raw_logging.h new file mode 100644 index 000000000000..418d6c856feb --- /dev/null +++ b/third_party/abseil_cpp/absl/base/internal/raw_logging.h @@ -0,0 +1,183 @@ +// Copyright 2017 The Abseil Authors. +// +// 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 +// +// https://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. +// +// Thread-safe logging routines that do not allocate any memory or +// acquire any locks, and can therefore be used by low-level memory +// allocation, synchronization, and signal-handling code. + +#ifndef ABSL_BASE_INTERNAL_RAW_LOGGING_H_ +#define ABSL_BASE_INTERNAL_RAW_LOGGING_H_ + +#include <string> + +#include "absl/base/attributes.h" +#include "absl/base/config.h" +#include "absl/base/internal/atomic_hook.h" +#include "absl/base/log_severity.h" +#include "absl/base/macros.h" +#include "absl/base/optimization.h" +#include "absl/base/port.h" + +// This is similar to LOG(severity) << format..., but +// * it is to be used ONLY by low-level modules that can't use normal LOG() +// * it is designed to be a low-level logger that does not allocate any +// memory and does not need any locks, hence: +// * it logs straight and ONLY to STDERR w/o buffering +// * it uses an explicit printf-format and arguments list +// * it will silently chop off really long message strings +// Usage example: +// ABSL_RAW_LOG(ERROR, "Failed foo with %i: %s", status, error); +// This will print an almost standard log line like this to stderr only: +// E0821 211317 file.cc:123] RAW: Failed foo with 22: bad_file + +#define ABSL_RAW_LOG(severity, ...) \ + do { \ + constexpr const char* absl_raw_logging_internal_basename = \ + ::absl::raw_logging_internal::Basename(__FILE__, \ + sizeof(__FILE__) - 1); \ + ::absl::raw_logging_internal::RawLog(ABSL_RAW_LOGGING_INTERNAL_##severity, \ + absl_raw_logging_internal_basename, \ + __LINE__, __VA_ARGS__); \ + } while (0) + +// Similar to CHECK(condition) << message, but for low-level modules: +// we use only ABSL_RAW_LOG that does not allocate memory. +// We do not want to provide args list here to encourage this usage: +// if (!cond) ABSL_RAW_LOG(FATAL, "foo ...", hard_to_compute_args); +// so that the args are not computed when not needed. +#define ABSL_RAW_CHECK(condition, message) \ + do { \ + if (ABSL_PREDICT_FALSE(!(condition))) { \ + ABSL_RAW_LOG(FATAL, "Check %s failed: %s", #condition, message); \ + } \ + } while (0) + +// ABSL_INTERNAL_LOG and ABSL_INTERNAL_CHECK work like the RAW variants above, +// except that if the richer log library is linked into the binary, we dispatch +// to that instead. This is potentially useful for internal logging and +// assertions, where we are using RAW_LOG neither for its async-signal-safety +// nor for its non-allocating nature, but rather because raw logging has very +// few other dependencies. +// +// The API is a subset of the above: each macro only takes two arguments. Use +// StrCat if you need to build a richer message. +#define ABSL_INTERNAL_LOG(severity, message) \ + do { \ + ::absl::raw_logging_internal::internal_log_function( \ + ABSL_RAW_LOGGING_INTERNAL_##severity, __FILE__, __LINE__, message); \ + } while (0) + +#define ABSL_INTERNAL_CHECK(condition, message) \ + do { \ + if (ABSL_PREDICT_FALSE(!(condition))) { \ + std::string death_message = "Check " #condition " failed: "; \ + death_message += std::string(message); \ + ABSL_INTERNAL_LOG(FATAL, death_message); \ + } \ + } while (0) + +#define ABSL_RAW_LOGGING_INTERNAL_INFO ::absl::LogSeverity::kInfo +#define ABSL_RAW_LOGGING_INTERNAL_WARNING ::absl::LogSeverity::kWarning +#define ABSL_RAW_LOGGING_INTERNAL_ERROR ::absl::LogSeverity::kError +#define ABSL_RAW_LOGGING_INTERNAL_FATAL ::absl::LogSeverity::kFatal +#define ABSL_RAW_LOGGING_INTERNAL_LEVEL(severity) \ + ::absl::NormalizeLogSeverity(severity) + +namespace absl { +ABSL_NAMESPACE_BEGIN +namespace raw_logging_internal { + +// Helper function to implement ABSL_RAW_LOG +// Logs format... at "severity" level, reporting it +// as called from file:line. +// This does not allocate memory or acquire locks. +void RawLog(absl::LogSeverity severity, const char* file, int line, + const char* format, ...) ABSL_PRINTF_ATTRIBUTE(4, 5); + +// Writes the provided buffer directly to stderr, in a safe, low-level manner. +// +// In POSIX this means calling write(), which is async-signal safe and does +// not malloc. If the platform supports the SYS_write syscall, we invoke that +// directly to side-step any libc interception. +void SafeWriteToStderr(const char *s, size_t len); + +// compile-time function to get the "base" filename, that is, the part of +// a filename after the last "/" or "\" path separator. The search starts at +// the end of the string; the second parameter is the length of the string. +constexpr const char* Basename(const char* fname, int offset) { + return offset == 0 || fname[offset - 1] == '/' || fname[offset - 1] == '\\' + ? fname + offset + : Basename(fname, offset - 1); +} + +// For testing only. +// Returns true if raw logging is fully supported. When it is not +// fully supported, no messages will be emitted, but a log at FATAL +// severity will cause an abort. +// +// TODO(gfalcon): Come up with a better name for this method. +bool RawLoggingFullySupported(); + +// Function type for a raw_logging customization hook for suppressing messages +// by severity, and for writing custom prefixes on non-suppressed messages. +// +// The installed hook is called for every raw log invocation. The message will +// be logged to stderr only if the hook returns true. FATAL errors will cause +// the process to abort, even if writing to stderr is suppressed. The hook is +// also provided with an output buffer, where it can write a custom log message +// prefix. +// +// The raw_logging system does not allocate memory or grab locks. User-provided +// hooks must avoid these operations, and must not throw exceptions. +// +// 'severity' is the severity level of the message being written. +// 'file' and 'line' are the file and line number where the ABSL_RAW_LOG macro +// was located. +// 'buffer' and 'buf_size' are pointers to the buffer and buffer size. If the +// hook writes a prefix, it must increment *buffer and decrement *buf_size +// accordingly. +using LogPrefixHook = bool (*)(absl::LogSeverity severity, const char* file, + int line, char** buffer, int* buf_size); + +// Function type for a raw_logging customization hook called to abort a process +// when a FATAL message is logged. If the provided AbortHook() returns, the +// logging system will call abort(). +// +// 'file' and 'line' are the file and line number where the ABSL_RAW_LOG macro +// was located. +// The NUL-terminated logged message lives in the buffer between 'buf_start' +// and 'buf_end'. 'prefix_end' points to the first non-prefix character of the +// buffer (as written by the LogPrefixHook.) +using AbortHook = void (*)(const char* file, int line, const char* buf_start, + const char* prefix_end, const char* buf_end); + +// Internal logging function for ABSL_INTERNAL_LOG to dispatch to. +// +// TODO(gfalcon): When string_view no longer depends on base, change this +// interface to take its message as a string_view instead. +using InternalLogFunction = void (*)(absl::LogSeverity severity, + const char* file, int line, + const std::string& message); + +ABSL_DLL ABSL_INTERNAL_ATOMIC_HOOK_ATTRIBUTES extern base_internal::AtomicHook< + InternalLogFunction> + internal_log_function; + +void RegisterInternalLogFunction(InternalLogFunction func); + +} // namespace raw_logging_internal +ABSL_NAMESPACE_END +} // namespace absl + +#endif // ABSL_BASE_INTERNAL_RAW_LOGGING_H_ |