1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
|
/*
* Copyright (C) 2020 The Android Open Source Project
*
* 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.
*/
#pragma once
#include <bitset>
#include <list>
#include <queue>
#include "LogBuffer.h"
#include "LogdLock.h"
#include "SerializedLogChunk.h"
#include "SerializedLogEntry.h"
struct LogPosition {
std::list<SerializedLogChunk>::iterator buffer_it;
int read_offset;
const SerializedLogEntry* log_entry() const { return buffer_it->log_entry(read_offset); }
};
struct LogWithId {
log_id_t log_id;
const SerializedLogEntry* entry;
};
// This class tracks the specific point where a FlushTo client has read through the logs. It
// directly references the std::list<> iterators from the parent SerializedLogBuffer and the offset
// into each log chunk where it has last read. All interactions with this class, except for its
// construction, must be done with SerializedLogBuffer::lock_ held.
class SerializedFlushToState : public FlushToState {
public:
// Initializes this state object. For each log buffer set in log_mask, this sets
// logs_needed_from_next_position_.
SerializedFlushToState(uint64_t start, LogMask log_mask, std::list<SerializedLogChunk>* logs)
REQUIRES(logd_lock);
// Decrease the reference of all referenced logs. This happens when a reader is disconnected.
~SerializedFlushToState() override;
// Updates the state of log_positions_ and logs_needed_from_next_position_ then returns true if
// there are any unread logs, false otherwise.
bool HasUnreadLogs() REQUIRES(logd_lock);
// Returns the next unread log and sets logs_needed_from_next_position_ to indicate that we're
// waiting for more logs from the associated log buffer.
LogWithId PopNextUnreadLog() REQUIRES(logd_lock);
// If the parent log buffer prunes logs, the reference that this class contains may become
// invalid, so this must be called first to drop the reference to buffer_it, if any.
void Prune(log_id_t log_id) REQUIRES(logd_lock);
private:
// Set logs_needed_from_next_position_[i] to indicate if log_positions_[i] points to an unread
// log or to the point at which the next log will appear.
void UpdateLogsNeeded(log_id_t log_id) REQUIRES(logd_lock);
// Create a LogPosition object for the given log_id by searching through the log chunks for the
// first chunk and then first log entry within that chunk that is greater or equal to start().
void CreateLogPosition(log_id_t log_id) REQUIRES(logd_lock);
// Checks to see if any log buffers set in logs_needed_from_next_position_ have new logs and
// calls UpdateLogsNeeded() if so.
void CheckForNewLogs() REQUIRES(logd_lock);
std::list<SerializedLogChunk>* logs_ GUARDED_BY(logd_lock) = nullptr;
// An optional structure that contains an iterator to the serialized log buffer and offset into
// it that this logger should handle next.
std::optional<LogPosition> log_positions_[LOG_ID_MAX] GUARDED_BY(logd_lock);
// A bit for each log that is set if a given log_id has no logs or if this client has read all
// of its logs. In order words: `logs_[i].empty() || (buffer_it == std::prev(logs_.end) &&
// next_log_position == logs_write_position_)`. These will be re-checked in each
// loop in case new logs came in.
std::bitset<LOG_ID_MAX> logs_needed_from_next_position_ GUARDED_BY(logd_lock) = {};
};
|
