mirror of
https://github.com/Mrs4s/go-cqhttp.git
synced 2025-05-04 19:17:37 +08:00
117 lines
2.9 KiB
Go
117 lines
2.9 KiB
Go
package btree
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import (
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"encoding/binary"
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"math/rand"
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"unsafe"
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)
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type chunk struct {
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offset int64
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len int
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}
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const freeQueueLen = 64
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func freeQueued(bt *DB) {
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for i := 0; i < bt.fqueueLen; i++ {
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chunk := &bt.fqueue[i]
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bt.freeChunk(chunk.offset, chunk.len)
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}
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bt.fqueueLen = 0
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}
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func (d *DB) allocChunk(size int) int64 {
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assert(size > 0)
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size = power2(size)
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var offset int64
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if d.inAllocator {
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const i32s = unsafe.Sizeof(int32(0))
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/* create fake size SHA-1 */
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var sha1 [hashSize]byte
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binary.LittleEndian.PutUint32(sha1[0*4:1*4], ^uint32(0)) // *(uint32_t *) hash = -1;
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binary.LittleEndian.PutUint32(sha1[1*4:2*4], uint32(size)) // ((__be32 *) hash)[1] = to_be32(size);
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/* find free chunk with the larger or the same size/SHA-1 */
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d.inAllocator = true
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d.deleteLarger = true
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offset = d.delete(d.freeTop, &sha1[0])
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d.deleteLarger = false
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if offset != 0 {
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flen := int(binary.LittleEndian.Uint32(sha1[:4])) // size_t free_len = from_be32(((__be32 *) hash)[1])
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assert(power2(flen) == flen)
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assert(flen >= size)
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/* delete buddy information */
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sha1 = [hashSize]byte{}
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binary.LittleEndian.PutUint64(sha1[0*8:1*8], uint64(offset))
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buddyLen := d.delete(d.freeTop, &sha1[0])
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assert(buddyLen == int64(size))
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d.freeTop = collapse(d, d.freeTop)
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d.inAllocator = false
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/* free extra space at the end of the chunk */
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for flen > size {
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flen >>= 1
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d.freeChunk(offset+int64(flen), flen)
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}
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} else {
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d.inAllocator = false
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}
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}
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if offset == 0 {
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/* not found, allocate from the end of the file */
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offset = d.alloc
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/* TODO: this wastes memory.. */
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if offset&int64(size-1) != 0 {
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offset += int64(size) - (offset & (int64(size) - 1))
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}
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d.alloc = offset + int64(size)
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}
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d.flushSuper()
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// make sure the allocation tree is up-to-date before using the chunk
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_ = d.fd.Sync()
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return offset
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}
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/* Mark a chunk as unused in the database file */
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func (d *DB) freeChunk(offset int64, size int) {
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assert(size > 0)
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assert(offset != 0)
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size = power2(size)
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assert(offset&int64(size-1) == 0)
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if d.inAllocator {
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chunk := &d.fqueue[d.fqueueLen]
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d.fqueueLen++
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chunk.offset = offset
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chunk.len = size
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return
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}
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/* create fake offset SHA-1 for buddy allocation */
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var sha1 [hashSize]byte
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d.inAllocator = true
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/* add buddy information */
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binary.LittleEndian.PutUint32(sha1[0*4:1*4], ^uint32(0)) // *(uint32_t *) hash = -1;
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binary.LittleEndian.PutUint32(sha1[1*4:2*4], uint32(size)) // ((__be32 *) hash)[1] = to_be32(size);
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binary.LittleEndian.PutUint32(sha1[2*4:3*4], rand.Uint32()) /* to make SHA-1 unique */
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binary.LittleEndian.PutUint32(sha1[3*4:4*4], rand.Uint32())
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// insert_toplevel(btree, &btree->free_top, hash, NULL, offset);
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_ = d.insertTopLevel(&d.freeTop, &sha1[0], nil, int(offset))
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d.inAllocator = false
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d.flushSuper()
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// make sure the allocation tree is up-to-date before removing
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// references to the chunk
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_ = d.fd.Sync()
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}
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