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30 lines
1.2 KiB
Go
30 lines
1.2 KiB
Go
//go:build (darwin || linux || freebsd || openbsd || netbsd || dragonfly || illumos || sqlite3_flock) && (386 || arm || amd64 || arm64 || riscv64 || ppc64le) && !(sqlite3_noshm || sqlite3_nosys)
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package vfs
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// SupportsSharedMemory is false on platforms that do not support shared memory.
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// To use [WAL without shared-memory], you need to set [EXCLUSIVE locking mode].
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//
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// [WAL without shared-memory]: https://sqlite.org/wal.html#noshm
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// [EXCLUSIVE locking mode]: https://sqlite.org/pragma.html#pragma_locking_mode
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const SupportsSharedMemory = true
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func (f *vfsFile) SharedMemory() SharedMemory { return f.shm }
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// NewSharedMemory returns a shared-memory WAL-index
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// backed by a file with the given path.
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// It will return nil if shared-memory is not supported,
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// or not appropriate for the given flags.
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// Only [OPEN_MAIN_DB] databases may need a WAL-index.
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// You must ensure all concurrent accesses to a database
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// use shared-memory instances created with the same path.
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func NewSharedMemory(path string, flags OpenFlag) SharedMemory {
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if flags&OPEN_MAIN_DB == 0 || flags&(OPEN_DELETEONCLOSE|OPEN_MEMORY) != 0 {
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return nil
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}
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return &vfsShm{
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path: path,
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readOnly: flags&OPEN_READONLY != 0,
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}
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}
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