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94 lines
1.9 KiB
94 lines
1.9 KiB
// Copyright (C) 2018 Yasuhiro Matsumoto <mattn.jp@gmail.com>.
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//
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// Use of this source code is governed by an MIT-style
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// license that can be found in the LICENSE file.
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// +build cgo
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// +build sqlite_unlock_notify
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package sqlite3
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/*
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#cgo CFLAGS: -DSQLITE_ENABLE_UNLOCK_NOTIFY
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#include <stdlib.h>
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#include <sqlite3-binding.h>
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extern void unlock_notify_callback(void *arg, int argc);
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*/
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import "C"
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import (
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"fmt"
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"math"
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"sync"
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"unsafe"
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)
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type unlock_notify_table struct {
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sync.Mutex
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seqnum uint
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table map[uint]chan struct{}
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}
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var unt unlock_notify_table = unlock_notify_table{table: make(map[uint]chan struct{})}
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func (t *unlock_notify_table) add(c chan struct{}) uint {
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t.Lock()
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defer t.Unlock()
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h := t.seqnum
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t.table[h] = c
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t.seqnum++
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return h
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}
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func (t *unlock_notify_table) remove(h uint) {
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t.Lock()
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defer t.Unlock()
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delete(t.table, h)
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}
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func (t *unlock_notify_table) get(h uint) chan struct{} {
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t.Lock()
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defer t.Unlock()
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c, ok := t.table[h]
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if !ok {
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panic(fmt.Sprintf("Non-existent key for unlcok-notify channel: %d", h))
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}
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return c
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}
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//export unlock_notify_callback
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func unlock_notify_callback(argv unsafe.Pointer, argc C.int) {
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for i := 0; i < int(argc); i++ {
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parg := ((*(*[(math.MaxInt32 - 1) / unsafe.Sizeof((*C.uint)(nil))]*[1]uint)(argv))[i])
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arg := *parg
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h := arg[0]
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c := unt.get(h)
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c <- struct{}{}
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}
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}
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//export unlock_notify_wait
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func unlock_notify_wait(db *C.sqlite3) C.int {
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// It has to be a bufferred channel to not block in sqlite_unlock_notify
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// as sqlite_unlock_notify could invoke the callback before it returns.
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c := make(chan struct{}, 1)
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defer close(c)
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h := unt.add(c)
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defer unt.remove(h)
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pargv := C.malloc(C.sizeof_uint)
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defer C.free(pargv)
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argv := (*[1]uint)(pargv)
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argv[0] = h
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if rv := C.sqlite3_unlock_notify(db, (*[0]byte)(C.unlock_notify_callback), unsafe.Pointer(pargv)); rv != C.SQLITE_OK {
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return rv
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}
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<-c
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return C.SQLITE_OK
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}
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