Use 8 bytes to store int64 components of database keys #107

silasdavis · 2018-08-30T15:05:50Z

This fixes #104 by introducing KeyFormat that uses a fixed-width key format over the full 8 bytes provided by int64 versions in orphan, and root keys. It also relies on the fixed width format to provide more efficient code for formatting into and scanning values from keys.

As a result of this it seems to lead to a ~10% speedup in BenchmarkTreeLoadAndDelete by avoiding the relatively expensive fmt.Sprintf and fmt.Sscanf functions, see below.

Before `KeyFormat` introduction

go test -bench=.
goos: linux
goarch: amd64
pkg: github.com/tendermint/iavl
BenchmarkNodeKey-8                 	 5000000	       316 ns/op
BenchmarkOrphanKey-8               	 2000000	       613 ns/op
ok, starting
BenchmarkImmutableAvlTreeMemDB-8   	200	   5783362 ns/op	 1104190 B/op	   22488 allocs/op
BenchmarkTreeLoadAndDelete/LoadAndDelete-8         	       2	 707800784 ns/op
PASS
ok  	github.com/tendermint/iavl	129.478s

After `KeyFormat` introduction

go test -bench=.
goos: linux
goarch: amd64
pkg: github.com/tendermint/iavl
BenchmarkNodeKey-8                 	30000000	        50.9 ns/op
BenchmarkOrphanKey-8               	 5000000	       256 ns/op
BenchmarkImmutableAvlTreeMemDB-8   	     500	   4048465 ns/op	   82591 B/op	    1546 allocs/op
BenchmarkTreeLoadAndDelete/LoadAndDelete-8         	       5	 641415439 ns/op
PASS
ok  	github.com/tendermint/iavl	121.982s

For BenchmarkTreeLoadAndDelete/LoadAndDelete-8 we have 1 - 641415439/707800784 ~= 9.3%

ValarDragon · 2018-08-30T15:09:20Z

This is an incredible performance win! I'm especially glad to see that the source of the large memory allocations is solved!
Does the key being negative matter?

silasdavis · 2018-08-30T15:18:35Z

proof_test.go

@@ -17,7 +17,7 @@ func TestTreeGetWithProof(t *testing.T) {
 	require := require.New(t)
 	for _, ikey := range []byte{0x11, 0x32, 0x50, 0x72, 0x99} {
 		key := []byte{ikey}
-		tree.Set(key, []byte(rand.Str(8)))
+		tree.Set(key, []byte(random.Str(8)))


I made this rename because rand clashes with standard math/rand which I wanted to use. I could of aliased by I thought it was better to avoid clashing with stdlib (maybe better still to not use a global...? (even better to perhaps do without tendermint/common :o - but I should tread lightly for now :) )).

silasdavis · 2018-08-30T15:19:05Z

testutils_test.go

 	for i := 0; i < 1000000; i++ {
-		t.Set(i2b(int(cmn.RandInt32())), nil)
+		t.Set(i2b(int(cmn.RandInt32())), value)


go test -bench=. was panicking on develop without this change

linking #76

silasdavis · 2018-08-30T15:41:51Z

@ValarDragon negative gives should be fine - I've added a test.

ValarDragon

This change looks great to me! Using this KeyFormat makes the code much cleaner / more readable.

However I'm unfamiliar with alot of the internals of iavl, so I'll leave it to @jlandrews, @liamsi to approve.

ValarDragon · 2018-09-04T00:26:46Z

Just want to note, this performance increase is actually super helpful for our state machine as well. Some benchmarks I was doing had the sprintf calls from GetNode and SaveAs as taking up 1.5% of the entire state machines time. (Includes goleveldb compaction)

liamsi

Awesome pull request. Thanks a lot @silasdavis 👍

Left a few nits/questions in the review. Will merge tonight.

liamsi · 2018-09-04T09:39:02Z

key_format.go

+	}
+}
+
+// Format the byte segments into the key format - will panic if the segment lengths to do match the layout.


will panic if the segment lengths to not match the layout.

liamsi · 2018-09-04T09:49:29Z

key_format.go

+	return string([]byte{kf.prefix})
+}
+
+func scan(a interface{}, value []byte) {


I would rename this to scanValue. Probably just a matter of preferences.

liamsi · 2018-09-04T09:50:33Z

key_format.go

+	return key[:n]
+}
+
+// Format the args passed into the key format - will panic if the arguments passed to not match the length


will panic if the arguments passed do not match the length

liamsi · 2018-09-04T09:56:13Z

key_format.go

+		binary.BigEndian.PutUint64(bs, uint64(v))
+		return bs
+	case int:
+		return format(int64(v))


Couldn't all these non-byte cases be simplified to:

case uint64, uint, int64, int: bs := make([]byte, 8) binary.BigEndian.PutUint64(bs, uint64(v)) return bs

?

When I read that I thought, oh really, how did I not know you could do that, but sadly you cannot. The compile-time type of v becomes interface{} as soon as you combine types which cannot be type converted.

You must have been confusing this with a language that has type system :)

I can make it a bit more consistent though:

func format(a interface{}) []byte { switch v := a.(type) { case uint64: bs := make([]byte, 8) binary.BigEndian.PutUint64(bs, v) return bs case uint: return format(uint64(v)) case int64: return format(uint64(v)) case int: return format(uint64(v)) case []byte: return v default: panic(fmt.Errorf("KeyFormat format() does not support formatting value of type %T: %v", a, a)) } }

I'd prefer not to do recursive calls, but instead have a second "formatuint64" function which all of these sub-cases call. A second interface conversions seems like an unnecessary performance hit, given that this may be called a ton.

liamsi · 2018-09-04T10:18:46Z

key_format.go

+}
+
+// Create a []byte key format based on a single byte prefix and fixed width key segments each of whose length is
+// specified by by the corresponding element of layout


Maybe, a little example would be great here?

liamsi · 2018-09-04T10:20:51Z

testutils_test.go

 	for i := 0; i < 1000000; i++ {
-		t.Set(i2b(int(cmn.RandInt32())), nil)
+		t.Set(i2b(int(cmn.RandInt32())), value)


linking #76

liamsi · 2018-09-04T10:24:22Z

key_format.go

+
+// Format the args passed into the key format - will panic if the arguments passed to not match the length
+// of the segment to which they correspond. When called with no arguments returns the raw prefix (useful as a start
+// element of the entire keys space when sorted lexicographically)


Nit: comments should end with a full stop (here and everywhere else). Don't bother, I'll add these.

liamsi · 2018-09-04T10:27:32Z

key_format.go

+	case *int64:
+		*v = int64(binary.BigEndian.Uint64(value))
+	case *uint64:
+		*v = binary.BigEndian.Uint64(value)


Question: Maybe I'm overlooking sth obvious here but why are there only two cases (int64 and uint64) when reading in the value? When formatting the we allow for uint64, uint, int64, int.

It's convenient to be able to call kf.Key(0, 1, 2) and not have to cast each argument, kf.Key(0) is the example that exists, and in tests.

liamsi · 2018-09-04T10:30:07Z

key_format.go

+func scan(a interface{}, value []byte) {
+	switch v := a.(type) {
+	case *int64:
+		*v = int64(binary.BigEndian.Uint64(value))


Will this still behave as intended when this overflows?

Yeah it's fine the MSB just becomes the sign bit - I've added a test to demonstrate. Provided the user is consistent with using int64 for signed numbers.

silasdavis · 2018-09-04T18:55:35Z

@liamsi I'll make these changes shortly - thanks.

Signed-off-by: Silas Davis <[email protected]>

…ids string manipulatio/scanning

scan function

silasdavis · 2018-09-04T19:42:49Z

@liamsi changes done

liamsi · 2018-09-05T15:45:30Z

Awesome! Merging and will prep a release this week.

See full changelog here: https://github.com/tendermint/iavl/blob/develop/CHANGELOG.md#0110-september-7-2018 * Update to CircleCI 2.0 (#108) * Use 8 bytes to store int64 components of database keys (#107) * Introduce KeyFormat that uses a full 8 bytes for int64 values and avoids string manipulatio/scanning * Add node key and orphan key benchmark * Fix various issue from PR: punctuation, add overflow test, and improve scan function * Remove architecture dependent getter functions (#96) * Remove architecture dependent getter functions * update changelog * Prep Release 0.11.0 (#111) * Bump version and update change-log

* 'develop' of github.com:danil-lashin/iavl: Prep Release 0.11.0 (cosmos#111) Remove architecture dependent getter functions (cosmos#96) Use 8 bytes to store int64 components of database keys (cosmos#107) Update to CircleCI 2.0 (cosmos#108) Release 0.10.0: Update Changelog and bump version (cosmos#99) delete empty file (relict from merging master into develop) Mutable/Immutable refactor and GetImmutable snapshots (cosmos#92) Remove unreachable code Remove unused variable dep: Change tendermint dep to be ^v0.22.0 (cosmos#91) Fix benchmark scripts for current code (cosmos#89) release v0.9.2 (cosmos#82) Various lints (cosmos#80) Jae/rangeprooffix (cosmos#75)

* Introduce KeyFormat that uses a full 8 bytes for int64 values and avoids string manipulatio/scanning * Add node key and orphan key benchmark * Fix various issue from PR: punctuation, add overflow test, and improve scan function

See full changelog here: https://github.com/tendermint/iavl/blob/develop/CHANGELOG.md#0110-september-7-2018 * Update to CircleCI 2.0 (cosmos#108) * Use 8 bytes to store int64 components of database keys (cosmos#107) * Introduce KeyFormat that uses a full 8 bytes for int64 values and avoids string manipulatio/scanning * Add node key and orphan key benchmark * Fix various issue from PR: punctuation, add overflow test, and improve scan function * Remove architecture dependent getter functions (cosmos#96) * Remove architecture dependent getter functions * update changelog * Prep Release 0.11.0 (cosmos#111) * Bump version and update change-log

silasdavis commented Aug 30, 2018

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silasdavis force-pushed the int64-versions branch 2 times, most recently from ca4bc10 to dc76584 Compare August 30, 2018 15:29

silasdavis mentioned this pull request Aug 30, 2018

Use 64-bit wide prefix rather than 10 decimal digits #104

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silasdavis force-pushed the int64-versions branch 3 times, most recently from 28d5706 to d125383 Compare August 30, 2018 15:53

ValarDragon reviewed Aug 30, 2018

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silasdavis force-pushed the int64-versions branch 3 times, most recently from a2a8ab4 to d265b7d Compare August 31, 2018 08:05

silasdavis changed the title ~~Use 8 bytes for keys with int64 components~~ Use 8 bytes to store int64 components of database keys Aug 31, 2018

liamsi reviewed Sep 4, 2018

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Silas Davis added 3 commits September 4, 2018 20:38

Add node key and orphan key benchmark

56dfbbb

Signed-off-by: Silas Davis <[email protected]>

Introduce KeyFormat that uses a full 8 bytes for int64 values and avo…

fc21828

…ids string manipulatio/scanning

Fix various issue from PR: punctuation, add overflow test, and improve

8290d65

scan function

silasdavis force-pushed the int64-versions branch from 100ed1e to 8290d65 Compare September 4, 2018 19:40

liamsi merged commit 9a73b02 into cosmos:develop Sep 5, 2018

silasdavis deleted the int64-versions branch September 5, 2018 15:47

silasdavis mentioned this pull request Sep 14, 2018

Refactor state into refs and tree. hyperledger-archives/burrow#912

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Use 8 bytes to store int64 components of database keys #107

Use 8 bytes to store int64 components of database keys #107

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Before KeyFormat introduction

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silasdavis commented Sep 4, 2018

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Before `KeyFormat` introduction

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