command.go (2497B)
1 // Copyright 2019 The Ebiten Authors 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 package buffered 16 17 import ( 18 "sync" 19 "sync/atomic" 20 ) 21 22 var ( 23 // delayedCommands represents a queue for image operations that are ordered before the game starts 24 // (BeginFrame). Before the game starts, the package shareable doesn't determine the minimum/maximum texture 25 // sizes (#879). 26 delayedCommands = []func() error{} 27 28 delayedCommandsM sync.Mutex 29 delayedCommandsFlushed uint32 30 ) 31 32 func flushDelayedCommands() error { 33 fs := getDelayedFuncsAndClear() 34 for _, f := range fs { 35 if err := f(); err != nil { 36 return err 37 } 38 } 39 return nil 40 41 } 42 43 func getDelayedFuncsAndClear() []func() error { 44 if atomic.LoadUint32(&delayedCommandsFlushed) == 0 { 45 // Outline the slow-path to expect the fast-path is inlined. 46 return getDelayedFuncsAndClearSlow() 47 } 48 return nil 49 } 50 51 func getDelayedFuncsAndClearSlow() []func() error { 52 delayedCommandsM.Lock() 53 defer delayedCommandsM.Unlock() 54 55 if delayedCommandsFlushed == 0 { 56 defer atomic.StoreUint32(&delayedCommandsFlushed, 1) 57 58 fs := make([]func() error, len(delayedCommands)) 59 copy(fs, delayedCommands) 60 delayedCommands = nil 61 return fs 62 } 63 64 return nil 65 } 66 67 // maybeCanAddDelayedCommand returns false if the delayed commands cannot be added. 68 // Otherwise, maybeCanAddDelayedCommand's returning value is not determined. 69 // For example, maybeCanAddDelayedCommand can return true even when flusing is being processed. 70 func maybeCanAddDelayedCommand() bool { 71 return atomic.LoadUint32(&delayedCommandsFlushed) == 0 72 } 73 74 func tryAddDelayedCommand(f func() error) bool { 75 delayedCommandsM.Lock() 76 defer delayedCommandsM.Unlock() 77 78 if delayedCommandsFlushed == 0 { 79 delayedCommands = append(delayedCommands, func() error { 80 return f() 81 }) 82 return true 83 } 84 85 return false 86 } 87 88 func checkDelayedCommandsFlushed(fname string) { 89 if atomic.LoadUint32(&delayedCommandsFlushed) == 0 { 90 panic("buffered: the command queue is not available yet at " + fname) 91 } 92 }