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
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
|
/*
* Copyright (C) 2012 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.
*/
#define LOG_TAG "MonoPipe"
//#define LOG_NDEBUG 0
#include <cutils/atomic.h>
#include <cutils/compiler.h>
#include <utils/Log.h>
#include <utils/Trace.h>
#include "MonoPipe.h"
#include "roundup.h"
namespace android {
MonoPipe::MonoPipe(size_t reqFrames, NBAIO_Format format, bool writeCanBlock) :
NBAIO_Sink(format),
mReqFrames(reqFrames),
mMaxFrames(roundup(reqFrames)),
mBuffer(malloc(mMaxFrames * Format_frameSize(format))),
mFront(0),
mRear(0),
mWriteTsValid(false),
// mWriteTs
mSetpoint((reqFrames * 11) / 16),
mWriteCanBlock(writeCanBlock)
{
}
MonoPipe::~MonoPipe()
{
free(mBuffer);
}
ssize_t MonoPipe::availableToWrite() const
{
if (CC_UNLIKELY(!mNegotiated)) {
return NEGOTIATE;
}
// uses mMaxFrames not mReqFrames, so allows "over-filling" the pipe beyond requested limit
ssize_t ret = mMaxFrames - (mRear - android_atomic_acquire_load(&mFront));
ALOG_ASSERT((0 <= ret) && (ret <= mMaxFrames));
return ret;
}
ssize_t MonoPipe::write(const void *buffer, size_t count)
{
if (CC_UNLIKELY(!mNegotiated)) {
return NEGOTIATE;
}
size_t totalFramesWritten = 0;
while (count > 0) {
// can't return a negative value, as we already checked for !mNegotiated
size_t avail = availableToWrite();
size_t written = avail;
if (CC_LIKELY(written > count)) {
written = count;
}
size_t rear = mRear & (mMaxFrames - 1);
size_t part1 = mMaxFrames - rear;
if (part1 > written) {
part1 = written;
}
if (CC_LIKELY(part1 > 0)) {
memcpy((char *) mBuffer + (rear << mBitShift), buffer, part1 << mBitShift);
if (CC_UNLIKELY(rear + part1 == mMaxFrames)) {
size_t part2 = written - part1;
if (CC_LIKELY(part2 > 0)) {
memcpy(mBuffer, (char *) buffer + (part1 << mBitShift), part2 << mBitShift);
}
}
android_atomic_release_store(written + mRear, &mRear);
totalFramesWritten += written;
}
if (!mWriteCanBlock) {
break;
}
count -= written;
buffer = (char *) buffer + (written << mBitShift);
// Simulate blocking I/O by sleeping at different rates, depending on a throttle.
// The throttle tries to keep the mean pipe depth near the setpoint, with a slight jitter.
uint32_t ns;
if (written > 0) {
size_t filled = (mMaxFrames - avail) + written;
// FIXME cache these values to avoid re-computation
if (filled <= mSetpoint / 2) {
// pipe is (nearly) empty, fill quickly
ns = written * ( 500000000 / Format_sampleRate(mFormat));
} else if (filled <= (mSetpoint * 3) / 4) {
// pipe is below setpoint, fill at slightly faster rate
ns = written * ( 750000000 / Format_sampleRate(mFormat));
} else if (filled <= (mSetpoint * 5) / 4) {
// pipe is at setpoint, fill at nominal rate
ns = written * (1000000000 / Format_sampleRate(mFormat));
} else if (filled <= (mSetpoint * 3) / 2) {
// pipe is above setpoint, fill at slightly slower rate
ns = written * (1150000000 / Format_sampleRate(mFormat));
} else if (filled <= (mSetpoint * 7) / 4) {
// pipe is overflowing, fill slowly
ns = written * (1350000000 / Format_sampleRate(mFormat));
} else {
// pipe is severely overflowing
ns = written * (1750000000 / Format_sampleRate(mFormat));
}
} else {
ns = count * (1350000000 / Format_sampleRate(mFormat));
}
if (ns > 999999999) {
ns = 999999999;
}
struct timespec nowTs;
bool nowTsValid = !clock_gettime(CLOCK_MONOTONIC, &nowTs);
// deduct the elapsed time since previous write() completed
if (nowTsValid && mWriteTsValid) {
time_t sec = nowTs.tv_sec - mWriteTs.tv_sec;
long nsec = nowTs.tv_nsec - mWriteTs.tv_nsec;
if (nsec < 0) {
--sec;
nsec += 1000000000;
}
if (sec == 0) {
if ((long) ns > nsec) {
ns -= nsec;
} else {
ns = 0;
}
}
}
if (ns > 0) {
const struct timespec req = {0, ns};
nanosleep(&req, NULL);
}
// record the time that this write() completed
if (nowTsValid) {
mWriteTs = nowTs;
if ((mWriteTs.tv_nsec += ns) >= 1000000000) {
mWriteTs.tv_nsec -= 1000000000;
++mWriteTs.tv_sec;
}
}
mWriteTsValid = nowTsValid;
}
mFramesWritten += totalFramesWritten;
return totalFramesWritten;
}
void MonoPipe::setAvgFrames(size_t setpoint)
{
mSetpoint = setpoint;
}
} // namespace android
|
