Fence.cpp revision 6fbefbbd8edc9953041289fbd77bb18c4964dce5 
1/*
2 * Copyright (C) 2012 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#define LOG_TAG "Fence"
18#define ATRACE_TAG ATRACE_TAG_GRAPHICS
19//#define LOG_NDEBUG 0
20
21// We would eliminate the non-conforming zero-length array, but we can't since
22// this is effectively included from the Linux kernel
23#pragma clang diagnostic push
24#pragma clang diagnostic ignored "-Wzero-length-array"
25#include <sync/sync.h>
26#pragma clang diagnostic pop
27
28#include <ui/Fence.h>
29#include <unistd.h>
30#include <utils/Log.h>
31#include <utils/Trace.h>
32
33namespace android {
34
35const sp<Fence> Fence::NO_FENCE = sp<Fence>(new Fence);
36
37Fence::Fence() :
38    mFenceFd(-1) {
39}
40
41Fence::Fence(int fenceFd) :
42    mFenceFd(fenceFd) {
43}
44
45Fence::~Fence() {
46    if (mFenceFd != -1) {
47        close(mFenceFd);
48    }
49}
50
51status_t Fence::wait(int timeout) {
52    ATRACE_CALL();
53    if (mFenceFd == -1) {
54        return NO_ERROR;
55    }
56    int err = sync_wait(mFenceFd, timeout);
57    return err < 0 ? -errno : status_t(NO_ERROR);
58}
59
60status_t Fence::waitForever(const char* logname) {
61    ATRACE_CALL();
62    if (mFenceFd == -1) {
63        return NO_ERROR;
64    }
65    int warningTimeout = 3000;
66    int err = sync_wait(mFenceFd, warningTimeout);
67    if (err < 0 && errno == ETIME) {
68        ALOGE("%s: fence %d didn't signal in %u ms", logname, mFenceFd,
69                warningTimeout);
70        err = sync_wait(mFenceFd, TIMEOUT_NEVER);
71    }
72    return err < 0 ? -errno : status_t(NO_ERROR);
73}
74
75sp<Fence> Fence::merge(const String8& name, const sp<Fence>& f1,
76        const sp<Fence>& f2) {
77    ATRACE_CALL();
78    int result;
79    // Merge the two fences.  In the case where one of the fences is not a
80    // valid fence (e.g. NO_FENCE) we merge the one valid fence with itself so
81    // that a new fence with the given name is created.
82    if (f1->isValid() && f2->isValid()) {
83        result = sync_merge(name.string(), f1->mFenceFd, f2->mFenceFd);
84    } else if (f1->isValid()) {
85        result = sync_merge(name.string(), f1->mFenceFd, f1->mFenceFd);
86    } else if (f2->isValid()) {
87        result = sync_merge(name.string(), f2->mFenceFd, f2->mFenceFd);
88    } else {
89        return NO_FENCE;
90    }
91    if (result == -1) {
92        status_t err = -errno;
93        ALOGE("merge: sync_merge(\"%s\", %d, %d) returned an error: %s (%d)",
94                name.string(), f1->mFenceFd, f2->mFenceFd,
95                strerror(-err), err);
96        return NO_FENCE;
97    }
98    return sp<Fence>(new Fence(result));
99}
100
101int Fence::dup() const {
102    return ::dup(mFenceFd);
103}
104
105nsecs_t Fence::getSignalTime() const {
106    if (mFenceFd == -1) {
107        return -1;
108    }
109
110    struct sync_fence_info_data* finfo = sync_fence_info(mFenceFd);
111    if (finfo == NULL) {
112        ALOGE("sync_fence_info returned NULL for fd %d", mFenceFd);
113        return -1;
114    }
115    if (finfo->status != 1) {
116        sync_fence_info_free(finfo);
117        return INT64_MAX;
118    }
119
120    struct sync_pt_info* pinfo = NULL;
121    uint64_t timestamp = 0;
122    while ((pinfo = sync_pt_info(finfo, pinfo)) != NULL) {
123        if (pinfo->timestamp_ns > timestamp) {
124            timestamp = pinfo->timestamp_ns;
125        }
126    }
127    sync_fence_info_free(finfo);
128
129    return nsecs_t(timestamp);
130}
131
132size_t Fence::getFlattenedSize() const {
133    return 4;
134}
135
136size_t Fence::getFdCount() const {
137    return isValid() ? 1 : 0;
138}
139
140status_t Fence::flatten(void*& buffer, size_t& size, int*& fds, size_t& count) const {
141    if (size < getFlattenedSize() || count < getFdCount()) {
142        return NO_MEMORY;
143    }
144    // Cast to uint32_t since the size of a size_t can vary between 32- and
145    // 64-bit processes
146    FlattenableUtils::write(buffer, size, static_cast<uint32_t>(getFdCount()));
147    if (isValid()) {
148        *fds++ = mFenceFd;
149        count--;
150    }
151    return NO_ERROR;
152}
153
154status_t Fence::unflatten(void const*& buffer, size_t& size, int const*& fds, size_t& count) {
155    if (mFenceFd != -1) {
156        // Don't unflatten if we already have a valid fd.
157        return INVALID_OPERATION;
158    }
159
160    if (size < 1) {
161        return NO_MEMORY;
162    }
163
164    uint32_t numFds;
165    FlattenableUtils::read(buffer, size, numFds);
166
167    if (numFds > 1) {
168        return BAD_VALUE;
169    }
170
171    if (count < numFds) {
172        return NO_MEMORY;
173    }
174
175    if (numFds) {
176        mFenceFd = *fds++;
177        count--;
178    }
179
180    return NO_ERROR;
181}
182
183} // namespace android
184