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| 3bd1f2 | 1 | // Copyright 2016 Tom Thorogood. All rights reserved. |
| Z | 2 | // Use of this source code is governed by a |
| 3 | // Modified BSD License license that can be found in | |
| 4 | // the LICENSE file. | |
| 5 | ||
| 6 | package shm | |
| 7 | ||
| 8 | import ( | |
| 9 | "golang.org/x/sys/unix" | |
| 10 | "os" | |
| 11 | "sync/atomic" | |
| 12 | "unsafe" | |
| 13 | ||
| 14 | "github.com/tmthrgd/go-sem" | |
| 15 | "github.com/tmthrgd/go-shm" | |
| 16 | ) | |
| 17 | ||
| 18 | func CreateSimplex(name string, perm os.FileMode, blockCount, blockSize int) (*ReadWriteCloser, error) { | |
| 19 | if blockSize&0x3f != 0 { | |
| 20 | return nil, ErrNotMultipleOf64 | |
| 21 | } | |
| 22 | ||
| 23 | file, err := shm.Open(name, unix.O_CREAT|unix.O_EXCL|unix.O_TRUNC|unix.O_RDWR, perm) | |
| 24 | if err != nil { | |
| 25 | return nil, err | |
| 26 | } | |
| 27 | ||
| 28 | defer file.Close() | |
| 29 | ||
| 30 | fullBlockSize := blockHeaderSize + uint64(blockSize) | |
| 31 | size := sharedHeaderSize + fullBlockSize*uint64(blockCount) | |
| 32 | ||
| 33 | if err = file.Truncate(int64(size)); err != nil { | |
| 34 | return nil, err | |
| 35 | } | |
| 36 | ||
| 37 | data, err := unix.Mmap(int(file.Fd()), 0, int(size), unix.PROT_READ|unix.PROT_WRITE, unix.MAP_SHARED) | |
| 38 | if err != nil { | |
| 39 | return nil, err | |
| 40 | } | |
| 41 | ||
| 42 | shared := (*sharedMem)(unsafe.Pointer(&data[0])) | |
| 43 | ||
| 44 | /* | |
| 45 | * memset already set: | |
| 46 | * shared.ReadStart, shared.ReadEnd = 0, 0 | |
| 47 | * shared.WriteStart, shared.WriteEnd = 0, 0 | |
| 48 | * shared.block[i].Size = 0 | |
| 49 | * shared.block[i].DoneRead, shared.block[i].DoneWrite = 0, 0 | |
| 50 | */ | |
| 51 | *(*uint32)(&shared.BlockCount), *(*uint64)(&shared.BlockSize) = uint32(blockCount), uint64(blockSize) | |
| 52 | ||
| 53 | if err = ((*sem.Semaphore)(&shared.SemSignal)).Init(0); err != nil { | |
| 54 | return nil, err | |
| 55 | } | |
| 56 | ||
| 57 | if err = ((*sem.Semaphore)(&shared.SemAvail)).Init(0); err != nil { | |
| 58 | return nil, err | |
| 59 | } | |
| 60 | ||
| 61 | for i := uint32(0); i < uint32(blockCount); i++ { | |
| 62 | block := (*sharedBlock)(unsafe.Pointer(&data[sharedHeaderSize+uint64(i)*fullBlockSize])) | |
| 63 | ||
| 64 | switch i { | |
| 65 | case 0: | |
| 66 | block.Next, *(*uint32)(&block.Prev) = 1, uint32(blockCount-1) | |
| 67 | case uint32(blockCount - 1): | |
| 68 | block.Next, *(*uint32)(&block.Prev) = 0, uint32(blockCount-2) | |
| 69 | default: | |
| 70 | *(*uint32)(&block.Next), *(*uint32)(&block.Prev) = i+1, i-1 | |
| 71 | } | |
| 72 | } | |
| 73 | ||
| 74 | atomic.StoreUint32((*uint32)(&shared.Version), version) | |
| 75 | ||
| 76 | return &ReadWriteCloser{ | |
| 77 | name: name, | |
| 78 | ||
| 79 | data: data, | |
| 80 | readShared: shared, | |
| 81 | writeShared: shared, | |
| 82 | size: size, | |
| 83 | fullBlockSize: fullBlockSize, | |
| 84 | ||
| 85 | Flags: (*[len(shared.Flags)]uint32)(unsafe.Pointer(&shared.Flags[0])), | |
| 86 | }, nil | |
| 87 | } | |
| 88 | ||
| 89 | func CreateDuplex(name string, perm os.FileMode, blockCount, blockSize int) (*ReadWriteCloser, error) { | |
| 90 | if blockSize&0x3f != 0 { | |
| 91 | return nil, ErrNotMultipleOf64 | |
| 92 | } | |
| 93 | ||
| 94 | file, err := shm.Open(name, unix.O_CREAT|unix.O_EXCL|unix.O_TRUNC|unix.O_RDWR, perm) | |
| 95 | if err != nil { | |
| 96 | return nil, err | |
| 97 | } | |
| 98 | ||
| 99 | defer file.Close() | |
| 100 | ||
| 101 | fullBlockSize := blockHeaderSize + uint64(blockSize) | |
| 102 | sharedSize := sharedHeaderSize + fullBlockSize*uint64(blockCount) | |
| 103 | size := 2 * sharedSize | |
| 104 | ||
| 105 | if err = file.Truncate(int64(size)); err != nil { | |
| 106 | return nil, err | |
| 107 | } | |
| 108 | ||
| 109 | data, err := unix.Mmap(int(file.Fd()), 0, int(size), unix.PROT_READ|unix.PROT_WRITE, unix.MAP_SHARED) | |
| 110 | if err != nil { | |
| 111 | return nil, err | |
| 112 | } | |
| 113 | ||
| 114 | for i := uint64(0); i < 2; i++ { | |
| 115 | shared := (*sharedMem)(unsafe.Pointer(&data[i*sharedSize])) | |
| 116 | ||
| 117 | /* | |
| 118 | * memset already set: | |
| 119 | * shared.ReadStart, shared.ReadEnd = 0, 0 | |
| 120 | * shared.WriteStart, shared.WriteEnd = 0, 0 | |
| 121 | * shared.Blocks[i].Size = 0 | |
| 122 | * shared.Blocks[i].DoneRead, shared.Blocks[i].DoneWrite = 0, 0 | |
| 123 | */ | |
| 124 | *(*uint32)(&shared.BlockCount), *(*uint64)(&shared.BlockSize) = uint32(blockCount), uint64(blockSize) | |
| 125 | ||
| 126 | if err = ((*sem.Semaphore)(&shared.SemSignal)).Init(0); err != nil { | |
| 127 | return nil, err | |
| 128 | } | |
| 129 | ||
| 130 | if err = ((*sem.Semaphore)(&shared.SemAvail)).Init(0); err != nil { | |
| 131 | return nil, err | |
| 132 | } | |
| 133 | ||
| 134 | for j := uint32(0); j < uint32(blockCount); j++ { | |
| 135 | block := (*sharedBlock)(unsafe.Pointer(&data[i*sharedSize+sharedHeaderSize+uint64(j)*fullBlockSize])) | |
| 136 | ||
| 137 | switch j { | |
| 138 | case 0: | |
| 139 | block.Next, *(*uint32)(&block.Prev) = 1, uint32(blockCount-1) | |
| 140 | case uint32(blockCount - 1): | |
| 141 | block.Next, *(*uint32)(&block.Prev) = 0, uint32(blockCount-2) | |
| 142 | default: | |
| 143 | *(*uint32)(&block.Next), *(*uint32)(&block.Prev) = j+1, j-1 | |
| 144 | } | |
| 145 | } | |
| 146 | } | |
| 147 | ||
| 148 | readShared := (*sharedMem)(unsafe.Pointer(&data[0])) | |
| 149 | atomic.StoreUint32((*uint32)(&readShared.Version), version) | |
| 150 | ||
| 151 | return &ReadWriteCloser{ | |
| 152 | name: name, | |
| 153 | ||
| 154 | data: data, | |
| 155 | readShared: readShared, | |
| 156 | writeShared: (*sharedMem)(unsafe.Pointer(&data[sharedSize])), | |
| 157 | size: size, | |
| 158 | fullBlockSize: fullBlockSize, | |
| 159 | ||
| 160 | Flags: (*[len(readShared.Flags)]uint32)(unsafe.Pointer(&readShared.Flags[0])), | |
| 161 | }, nil | |
| 162 | } | |
