log_format.h (3033B)
1 // Copyright 2022 The Abseil Authors. 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // https://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 // 15 // ----------------------------------------------------------------------------- 16 // File: log/internal/log_format.h 17 // ----------------------------------------------------------------------------- 18 // 19 // This file declares routines implementing formatting of log message and log 20 // prefix. 21 22 #ifndef ABSL_LOG_INTERNAL_LOG_FORMAT_H_ 23 #define ABSL_LOG_INTERNAL_LOG_FORMAT_H_ 24 25 #include <stddef.h> 26 27 #include <string> 28 29 #include "absl/base/config.h" 30 #include "absl/base/log_severity.h" 31 #include "absl/log/internal/config.h" 32 #include "absl/strings/string_view.h" 33 #include "absl/time/civil_time.h" 34 #include "absl/time/time.h" 35 #include "absl/types/span.h" 36 37 namespace absl { 38 ABSL_NAMESPACE_BEGIN 39 namespace log_internal { 40 41 enum class PrefixFormat { 42 kNotRaw, 43 kRaw, 44 }; 45 46 // Formats log message based on provided data. 47 std::string FormatLogMessage(absl::LogSeverity severity, 48 absl::CivilSecond civil_second, 49 absl::Duration subsecond, log_internal::Tid tid, 50 absl::string_view basename, int line, 51 PrefixFormat format, absl::string_view message); 52 53 // Formats various entry metadata into a text string meant for use as a 54 // prefix on a log message string. Writes into `buf`, advances `buf` to point 55 // at the remainder of the buffer (i.e. past any written bytes), and returns the 56 // number of bytes written. 57 // 58 // In addition to calling `buf->remove_prefix()` (or the equivalent), this 59 // function may also do `buf->remove_suffix(buf->size())` in cases where no more 60 // bytes (i.e. no message data) should be written into the buffer. For example, 61 // if the prefix ought to be: 62 // I0926 09:00:00.000000 1234567 foo.cc:123] 63 // `buf` is too small, the function might fill the whole buffer: 64 // I0926 09:00:00.000000 1234 65 // (note the apparrently incorrect thread ID), or it might write less: 66 // I0926 09:00:00.000000 67 // In this case, it might also empty `buf` prior to returning to prevent 68 // message data from being written into the space where a reader would expect to 69 // see a thread ID. 70 size_t FormatLogPrefix(absl::LogSeverity severity, absl::Time timestamp, 71 log_internal::Tid tid, absl::string_view basename, 72 int line, PrefixFormat format, absl::Span<char>& buf); 73 74 } // namespace log_internal 75 ABSL_NAMESPACE_END 76 } // namespace absl 77 78 #endif // ABSL_LOG_INTERNAL_LOG_FORMAT_H_