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repository/master_index: Optimize Index.Lookup()

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When looking up a blob in the master index, with several
indexes present in the master index, a significant amount of time
is spent generating errors for each failed lookup.  However, these
errors are often used to check if a blob is present, but the contents
are not inspected making the overhead of the error not useful.

Instead, change Index.Lookup (and Index.LookupSize) to instead return
a boolean denoting if the blob was found instead of an error.  Also change
all the calls to these functions to handle the new function signature.

benchmark                                            old ns/op     new ns/op     delta
BenchmarkMasterIndexLookupSingleIndex-6              820           897           +9.39%
BenchmarkMasterIndexLookupMultipleIndex-6            12821         2001          -84.39%
BenchmarkMasterIndexLookupSingleIndexUnknown-6       5378          492           -90.85%
BenchmarkMasterIndexLookupMultipleIndexUnknown-6     17026         1649          -90.31%

benchmark                                            old allocs     new allocs     delta
BenchmarkMasterIndexLookupSingleIndex-6              9              9              +0.00%
BenchmarkMasterIndexLookupMultipleIndex-6            59             19             -67.80%
BenchmarkMasterIndexLookupSingleIndexUnknown-6       22             6              -72.73%
BenchmarkMasterIndexLookupMultipleIndexUnknown-6     72             16             -77.78%

benchmark                                            old bytes     new bytes     delta
BenchmarkMasterIndexLookupSingleIndex-6              160           160           +0.00%
BenchmarkMasterIndexLookupMultipleIndex-6            3200          240           -92.50%
BenchmarkMasterIndexLookupSingleIndexUnknown-6       1232          48            -96.10%
BenchmarkMasterIndexLookupMultipleIndexUnknown-6     4272          128           -97.00%
This commit is contained in:
Matthew Dawson
2018-01-12 01:20:12 -05:00
parent ebce4b2581
commit df2c03a6a4
15 changed files with 192 additions and 68 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
internal/fuse/file.go
View File

@@ -4,6 +4,7 @@
package fuse
import (
"github.com/restic/restic/internal/errors"
"github.com/restic/restic/internal/restic"
"github.com/restic/restic/internal/debug"
@@ -36,9 +37,10 @@ func newFile(ctx context.Context, root *Root, inode uint64, node *restic.Node) (
for i, id := range node.Content {
size, ok := root.blobSizeCache.Lookup(id)
if !ok {
size, err = root.repo.LookupBlobSize(id, restic.DataBlob)
if err != nil {
return nil, err
var found bool
size, found = root.repo.LookupBlobSize(id, restic.DataBlob)
if !found {
return nil, errors.Errorf("id %v not found in repository", id)
}
}

4
internal/fuse/file_test.go
View File

@@ -81,8 +81,8 @@ func TestFuseFile(t *testing.T) {
memfile []byte
)
for _, id := range content {
size, err := repo.LookupBlobSize(id, restic.DataBlob)
rtest.OK(t, err)
size, found := repo.LookupBlobSize(id, restic.DataBlob)
rtest.Assert(t, found, "Expected to find blob id %v", id)
filesize += uint64(size)
buf := restic.NewBlobBuffer(int(size))