diff options
Diffstat (limited to 'src/chunklist.go')
| -rw-r--r-- | src/chunklist.go | 48 |
1 files changed, 44 insertions, 4 deletions
diff --git a/src/chunklist.go b/src/chunklist.go index cd635c25..91177b17 100644 --- a/src/chunklist.go +++ b/src/chunklist.go @@ -48,7 +48,12 @@ func CountItems(cs []*Chunk) int { if len(cs) == 0 { return 0 } - return chunkSize*(len(cs)-1) + cs[len(cs)-1].count + if len(cs) == 1 { + return cs[0].count + } + + // First chunk might not be full due to --tail=N + return cs[0].count + chunkSize*(len(cs)-2) + cs[len(cs)-1].count } // Push adds the item to the list @@ -72,18 +77,53 @@ func (cl *ChunkList) Clear() { } // Snapshot returns immutable snapshot of the ChunkList -func (cl *ChunkList) Snapshot() ([]*Chunk, int) { +func (cl *ChunkList) Snapshot(tail int) ([]*Chunk, int, bool) { cl.mutex.Lock() + changed := false + if tail > 0 && CountItems(cl.chunks) > tail { + changed = true + // Find the number of chunks to keep + numChunks := 0 + for left, i := tail, len(cl.chunks)-1; left > 0 && i >= 0; i-- { + numChunks++ + left -= cl.chunks[i].count + } + + // Copy the chunks to keep + ret := make([]*Chunk, numChunks) + copy(ret, cl.chunks[len(cl.chunks)-numChunks:]) + + for left, i := tail, len(ret)-1; i >= 0; i-- { + chunk := ret[i] + if chunk.count > left { + newChunk := *chunk + newChunk.count = left + oldCount := chunk.count + for i := 0; i < left; i++ { + newChunk.items[i] = chunk.items[oldCount-left+i] + } + ret[i] = &newChunk + break + } + left -= chunk.count + } + cl.chunks = ret + } + ret := make([]*Chunk, len(cl.chunks)) copy(ret, cl.chunks) - // Duplicate the last chunk + // Duplicate the first and the last chunk if cnt := len(ret); cnt > 0 { + if tail > 0 && cnt > 1 { + newChunk := *ret[0] + ret[0] = &newChunk + } newChunk := *ret[cnt-1] ret[cnt-1] = &newChunk } cl.mutex.Unlock() - return ret, CountItems(ret) + return ret, CountItems(ret), changed } |