d36c6be529
Noticed during my audit, the code for cache.CommitKVStoreCacheManager.Reset()
discarded the prior on every invocation i.e.
m = make(map[T(key)]T(value))
However, this can be made fast and conserve memory by using the map clearing idiom
that the Go compiler recognizes i.e.
for key := range m {
delete(m, key)
}
and turns into very fast code, instead of the extraneous map discarding.
The speed up generated is:
```shell
$ benchstat before after
name old time/op new time/op delta
Reset-8 204ns ± 2% 66ns ± 9% -67.86% (p=0.000 n=20+20)
name old alloc/op new alloc/op delta
Reset-8 384B ± 0% 0B -100.00% (p=0.000 n=20+20)
name old allocs/op new allocs/op delta
Reset-8 3.00 ± 0% 0.00 -100.00% (p=0.000 n=20+20)
```
Fixes #6681
49 lines
953 B
Go
49 lines
953 B
Go
package cache
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import (
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"testing"
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"github.com/cosmos/cosmos-sdk/store/types"
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)
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func freshMgr() *CommitKVStoreCacheManager {
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return &CommitKVStoreCacheManager{
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caches: map[string]types.CommitKVStore{
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"a1": nil,
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"alalalalalal": nil,
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},
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}
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}
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func populate(mgr *CommitKVStoreCacheManager) {
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mgr.caches["this one"] = (types.CommitKVStore)(nil)
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mgr.caches["those ones are the ones"] = (types.CommitKVStore)(nil)
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mgr.caches["very huge key right here and there are we going to ones are the ones"] = (types.CommitKVStore)(nil)
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}
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func BenchmarkReset(b *testing.B) {
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mgr := freshMgr()
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b.ResetTimer()
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b.ReportAllocs()
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for i := 0; i < b.N; i++ {
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mgr.Reset()
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if len(mgr.caches) != 0 {
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b.Fatal("Reset failed")
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}
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populate(mgr)
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if len(mgr.caches) == 0 {
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b.Fatal("populate failed")
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}
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mgr.Reset()
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if len(mgr.caches) != 0 {
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b.Fatal("Reset failed")
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}
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}
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if mgr == nil {
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b.Fatal("Impossible condition")
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}
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}
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