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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

20
internal/repository/index_test.go
View File

@@ -65,8 +65,8 @@ func TestIndexSerialize(t *testing.T) {
rtest.OK(t, err)
for _, testBlob := range tests {
list, err := idx.Lookup(testBlob.id, testBlob.tpe)
rtest.OK(t, err)
list, found := idx.Lookup(testBlob.id, testBlob.tpe)
rtest.Assert(t, found, "Expected to find blob id %v", testBlob.id.Str())
if len(list) != 1 {
t.Errorf("expected one result for blob %v, got %v: %v", testBlob.id.Str(), len(list), list)
@@ -78,8 +78,8 @@ func TestIndexSerialize(t *testing.T) {
rtest.Equals(t, testBlob.offset, result.Offset)
rtest.Equals(t, testBlob.length, result.Length)
list2, err := idx2.Lookup(testBlob.id, testBlob.tpe)
rtest.OK(t, err)
list2, found := idx2.Lookup(testBlob.id, testBlob.tpe)
rtest.Assert(t, found, "Expected to find blob id %v", testBlob.id)
if len(list2) != 1 {
t.Errorf("expected one result for blob %v, got %v: %v", testBlob.id.Str(), len(list2), list2)
@@ -146,8 +146,8 @@ func TestIndexSerialize(t *testing.T) {
// all new blobs must be in the index
for _, testBlob := range newtests {
list, err := idx3.Lookup(testBlob.id, testBlob.tpe)
rtest.OK(t, err)
list, found := idx3.Lookup(testBlob.id, testBlob.tpe)
rtest.Assert(t, found, "Expected to find blob id %v", testBlob.id.Str())
if len(list) != 1 {
t.Errorf("expected one result for blob %v, got %v: %v", testBlob.id.Str(), len(list), list)
@@ -293,8 +293,8 @@ func TestIndexUnserialize(t *testing.T) {
rtest.OK(t, err)
for _, test := range exampleTests {
list, err := idx.Lookup(test.id, test.tpe)
rtest.OK(t, err)
list, found := idx.Lookup(test.id, test.tpe)
rtest.Assert(t, found, "Expected to find blob id %v", test.id.Str())
if len(list) != 1 {
t.Errorf("expected one result for blob %v, got %v: %v", test.id.Str(), len(list), list)
@@ -341,8 +341,8 @@ func TestIndexUnserializeOld(t *testing.T) {
rtest.OK(t, err)
for _, test := range exampleTests {
list, err := idx.Lookup(test.id, test.tpe)
rtest.OK(t, err)
list, found := idx.Lookup(test.id, test.tpe)
rtest.Assert(t, found, "Expected to find blob id %v", test.id.Str())
if len(list) != 1 {
t.Errorf("expected one result for blob %v, got %v: %v", test.id.Str(), len(list), list)