1 /*
2 * Copyright 2017 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8 #include "SkTaskGroup2D.h"
9
start()10 void SkTaskGroup2D::start() {
11 fThreadsGroup->batch(fThreadCnt, [this](int threadId){
12 this->work(threadId);
13 });
14 }
15
addColumn()16 void SkTaskGroup2D::addColumn() {
17 SkASSERT(!fIsFinishing); // we're not supposed to add more work after the calling of finish
18 fWidth++;
19 }
20
finish()21 void SkTaskGroup2D::finish() {
22 fIsFinishing.store(true, std::memory_order_relaxed);
23 fThreadsGroup->wait();
24 }
25
work(int threadId)26 void SkSpinningTaskGroup2D::work(int threadId) {
27 int workCol = 0;
28 int initCol = 0;
29
30 while (true) {
31 SkASSERT(workCol <= fWidth);
32 if (this->isFinishing() && workCol >= fWidth) {
33 return;
34 }
35
36 // Note that row = threadId
37 if (workCol < fWidth && fKernel->work2D(threadId, workCol, threadId)) {
38 workCol++;
39 } else {
40 // Initialize something if we can't work
41 this->initAnUninitializedColumn(initCol, threadId);
42 }
43 }
44 }
45
work(int threadId)46 void SkFlexibleTaskGroup2D::work(int threadId) {
47 int row = threadId;
48 int initCol = 0;
49 int numRowsCompleted = 0;
50 std::vector<bool> completedRows(fHeight, false);
51
52 // Only keep fHeight - numRowsCompleted number of threads looping. When rows are about to
53 // complete, this strategy keeps the contention low.
54 while (threadId < fHeight - numRowsCompleted) {
55 RowData& rowData = fRowData[row];
56
57 // The Android roller somehow gets a false-positive compile warning/error about the try-lock
58 // and unlock process. Hence we disable -Wthread-safety-analysis to bypass it.
59 #ifdef __clang__
60 #pragma clang diagnostic push
61 #pragma clang diagnostic ignored "-Wthread-safety-analysis"
62 #endif
63 if (rowData.fMutex.try_acquire()) {
64 while (rowData.fNextColumn < fWidth &&
65 fKernel->work2D(row, rowData.fNextColumn, threadId)) {
66 rowData.fNextColumn++;
67 }
68 // isFinishing can never go from true to false. Once it's true, we count how many rows
69 // are completed (out of work). If that count reaches fHeight, then we're out of work
70 // for the whole group and we can stop.
71 if (rowData.fNextColumn == fWidth && this->isFinishing()) {
72 numRowsCompleted += (completedRows[row] == false);
73 completedRows[row] = true; // so we won't count this row twice
74 }
75 rowData.fMutex.release();
76 }
77 #ifdef __clang__
78 #pragma clang diagnostic pop
79 #endif
80
81 // By reaching here, we're either unable to acquire the row, or out of work, or blocked by
82 // initialization
83 row = (row + 1) % fHeight; // Move to the next row
84 this->initAnUninitializedColumn(initCol, threadId); // Initialize something
85 }
86 }
87