// Copyright 2022 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.

//

// -----------------------------------------------------------------------------

// File: log/log_entry.h

// -----------------------------------------------------------------------------

//

// This header declares `class absl::LogEntry`, which represents a log record as

// passed to `LogSink::Send`. Data returned by pointer or by reference or by

// `absl::string_view` must be copied if they are needed after the lifetime of

// the `absl::LogEntry`.

#ifndef ABSL_LOG_LOG_ENTRY_H_

#define ABSL_LOG_LOG_ENTRY_H_

#include <cstddef>

#include <string>

#include "absl/base/attributes.h"

#include "absl/base/config.h"

#include "absl/base/log_severity.h"

#include "absl/log/internal/config.h"

#include "absl/strings/string_view.h"

#include "absl/time/time.h"

#include "absl/types/span.h"

namespace absl {

ABSL_NAMESPACE_BEGIN

namespace log_internal {

// Test only friend.

class LogEntryTestPeer;

class LogMessage;

}  // namespace log_internal

// LogEntry

//

// Represents a single entry in a log, i.e., one `LOG` statement or failed

// `CHECK`.

//

// `LogEntry` is thread-compatible.

class LogEntry final {

 public:

  using tid_t = log_internal::Tid;

  // For non-verbose log entries, `verbosity()` returns `kNoVerbosityLevel`.

  static constexpr int kNoVerbosityLevel = -1;

  static constexpr int kNoVerboseLevel = -1;  // TO BE removed

  // Pass `LogEntry` by reference, and do not store it as its state does not

  // outlive the call to `LogSink::Send()`.

  LogEntry(const LogEntry&) = delete;

  LogEntry& operator=(const LogEntry&) = delete;

  // Source file and line where the log message occurred.  Taken from `__FILE__`

  // and `__LINE__` unless overridden by `LOG(...).AtLocation(...)`.

  //

  // Take special care not to use the values returned by `source_filename()` and

  // `source_basename()` after the lifetime of the entry.  This is always

  // incorrect, but it will often work in practice because they usually point

  // into a statically allocated character array obtained from `__FILE__`.

  // Statements like `LOG(INFO).AtLocation(std::string(...), ...)` will expose

  // the bug.  If you need the data later, you must copy them.

  absl::string_view source_filename() const ABSL_ATTRIBUTE_LIFETIME_BOUND {

    return full_filename_;

  }

  absl::string_view source_basename() const ABSL_ATTRIBUTE_LIFETIME_BOUND {

    return base_filename_;

  }

  int source_line() const { return line_; }

  // LogEntry::prefix()

  //

  // True unless the metadata prefix was suppressed once by

  // `LOG(...).NoPrefix()` or globally by `absl::EnableLogPrefix(false)`.

  // Implies `text_message_with_prefix() == text_message()`.

  bool prefix() const { return prefix_; }

  // LogEntry::log_severity()

  //

  // Returns this entry's severity.  For `LOG`, taken from the first argument;

  // for `CHECK`, always `absl::LogSeverity::kFatal`.

  absl::LogSeverity log_severity() const { return severity_; }

  // LogEntry::verbosity()

  //

  // Returns this entry's verbosity, or `kNoVerbosityLevel` for a non-verbose

  // entry. Taken from the argument to `VLOG` or from

  // `LOG(...).WithVerbosity(...)`.

  int verbosity() const { return verbose_level_; }

  // LogEntry::timestamp()

  //

  // Returns the time at which this entry was written.  Captured during

  // evaluation of `LOG`, but can be overridden by

  // `LOG(...).WithTimestamp(...)`.

  //

  // Take care not to rely on timestamps increasing monotonically, or even to

  // rely on timestamps having any particular relationship with reality (since

  // they can be overridden).

  absl::Time timestamp() const { return timestamp_; }

  // LogEntry::tid()

  //

  // Returns the ID of the thread that wrote this entry.  Captured during

  // evaluation of `LOG`, but can be overridden by `LOG(...).WithThreadID(...)`.

  //

  // Take care not to *rely* on reported thread IDs as they can be overridden as

  // specified above.

  tid_t tid() const { return tid_; }

  // Text-formatted version of the log message.  An underlying buffer holds

  // these contiguous data:

  //

  // * A prefix formed by formatting metadata (timestamp, filename, line number,

  //   etc.)

  //   The prefix may be empty - see `LogEntry::prefix()` - and may rarely be

  //   truncated if the metadata are very long.

  // * The streamed data

  //   The data may be empty if nothing was streamed, or may be truncated to fit

  //   the buffer.

  // * A newline

  // * A nul terminator

  //

  // The newline and nul terminator will be present even if the prefix and/or

  // data are truncated.

  //

  // These methods give access to the most commonly useful substrings of the

  // buffer's contents.  Other combinations can be obtained with substring

  // arithmetic.

  //

  // The buffer does not outlive the entry; if you need the data later, you must

  // copy them.

  absl::string_view text_message_with_prefix_and_newline() const

      ABSL_ATTRIBUTE_LIFETIME_BOUND {

    return absl::string_view(

        text_message_with_prefix_and_newline_and_nul_.data(),

        text_message_with_prefix_and_newline_and_nul_.size() - 1);

  }

  absl::string_view text_message_with_prefix() const

      ABSL_ATTRIBUTE_LIFETIME_BOUND {

    return absl::string_view(

        text_message_with_prefix_and_newline_and_nul_.data(),

        text_message_with_prefix_and_newline_and_nul_.size() - 2);

  }

  absl::string_view text_message_with_newline() const

      ABSL_ATTRIBUTE_LIFETIME_BOUND {

    return absl::string_view(

        text_message_with_prefix_and_newline_and_nul_.data() + prefix_len_,

        text_message_with_prefix_and_newline_and_nul_.size() - prefix_len_ - 1);

  }

  absl::string_view text_message() const ABSL_ATTRIBUTE_LIFETIME_BOUND {

    return absl::string_view(

        text_message_with_prefix_and_newline_and_nul_.data() + prefix_len_,

        text_message_with_prefix_and_newline_and_nul_.size() - prefix_len_ - 2);

  }

  const char* text_message_with_prefix_and_newline_c_str() const

      ABSL_ATTRIBUTE_LIFETIME_BOUND {

    return text_message_with_prefix_and_newline_and_nul_.data();

  }

  // Returns a serialized protobuf holding the operands streamed into this

  // log message.  The message definition is not yet published.

  //

  // The buffer does not outlive the entry; if you need the data later, you must

  // copy them.

  absl::string_view encoded_message() const ABSL_ATTRIBUTE_LIFETIME_BOUND {

    return encoding_;

  }

  // LogEntry::stacktrace()

  //

  // Optional stacktrace, e.g. for `FATAL` logs and failed `CHECK`s.

  //

  // Fatal entries are dispatched to each sink twice: first with all data and

  // metadata but no stacktrace, and then with the stacktrace.  This is done

  // because stacktrace collection is sometimes slow and fallible, and it's

  // critical to log enough information to diagnose the failure even if the

  // stacktrace collection hangs.

  //

  // The buffer does not outlive the entry; if you need the data later, you must

  // copy them.

  absl::string_view stacktrace() const ABSL_ATTRIBUTE_LIFETIME_BOUND {

    return stacktrace_;

  }

 private:

  LogEntry() = default;

  absl::string_view full_filename_;

  absl::string_view base_filename_;

  int line_;

  bool prefix_;

  absl::LogSeverity severity_;

  int verbose_level_;  // >=0 for `VLOG`, etc.; otherwise `kNoVerbosityLevel`.

  absl::Time timestamp_;

  tid_t tid_;

  absl::Span<const char> text_message_with_prefix_and_newline_and_nul_;

  size_t prefix_len_;

  absl::string_view encoding_;

  std::string stacktrace_;

  friend class log_internal::LogEntryTestPeer;

  friend class log_internal::LogMessage;

};

ABSL_NAMESPACE_END

}  // namespace absl

#endif  // ABSL_LOG_LOG_ENTRY_H_