overwrite optimization for dagmodifier
Jeromy committed
Mar 10, 2015 at 00:31 UTC
5ead2a9fab8fe588c494346103de6331f08db4ac
2 files changed
+8
-2
unixfs/mod/dagmodifier.go
+8
-1
@@ -63,7 +63,12 @@ func (dm *DagModifier) WriteAt(b []byte, offset int64) (int, error) {
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// TODO: this is currently VERY inneficient
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// each write that happens at an offset other than the current one causes a
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// flush to disk, and dag rewrite
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- if uint64(offset) != dm.curWrOff {
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+ if offset == int64(dm.writeStart) && dm.wrBuf != nil {
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+ // If we would overwrite the previous write
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+ if len(b) >= dm.wrBuf.Len() {
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+ dm.wrBuf.Reset()
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+ }
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+ } else if uint64(offset) != dm.curWrOff {
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size, err := dm.Size()
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if err != nil {
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return 0, err
@@ -242,6 +247,7 @@ func (dm *DagModifier) modifyDag(node *mdag.Node, offset uint64, data io.Reader)
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var cur uint64
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var done bool
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for i, bs := range f.GetBlocksizes() {
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+ // We found the correct child to write into
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if cur+bs > offset {
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child, err := node.Links[i].GetNode(dm.dagserv)
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if err != nil {
@@ -256,6 +262,7 @@ func (dm *DagModifier) modifyDag(node *mdag.Node, offset uint64, data io.Reader)
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node.Links[i].Hash = mh.Multihash(k)
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if sdone {
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+ // No more bytes to write!
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done = true
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break
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}
unixfs/mod/dagmodifier_test.go
-1
@@ -314,7 +314,6 @@ func TestMultiWriteCoal(t *testing.T) {
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u.NewTimeSeededRand().Read(data)
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for i := 0; i < len(data); i++ {
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- log.Error(i)
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n, err := dagmod.WriteAt(data[:i+1], 0)
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if err != nil {
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fmt.Println("FAIL AT ", i)