5a7569a5d3
When repositories have a large number (hundreds of thousands) of refs, Git LFS adds noticeable overhead on the time taken by `git show-ref` and `git ls-remote`. To reduce this overhead: * Avoid regular expressions when parsing lines of Git command output. Regexp evaluation was the most expensive part of this process in profiling. * Minimize the number of loops when computing skipped refs by combining the missing and skipped checks and converting the list of remote refs into a pre-filtered set. In a repository with ~300k remote references, these changes reduce the time spent in the pre-push command from 8.26s to 6.31s.
39 lines
1.5 KiB
Go
39 lines
1.5 KiB
Go
package lfs
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import (
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"github.com/git-lfs/git-lfs/git"
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"github.com/git-lfs/git-lfs/tools"
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)
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// calcSkippedRefs checks that locally cached versions of remote refs are still
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// present on the remote before they are used as a 'from' point. If the server
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// implements garbage collection and a remote branch had been deleted since we
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// last did 'git fetch --prune', then the objects in that branch may have also
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// been deleted on the server if unreferenced. If some refs are missing on the
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// remote, use a more explicit diff command.
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func calcSkippedRefs(remote string) []string {
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cachedRemoteRefs, _ := git.CachedRemoteRefs(remote)
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actualRemoteRefs, _ := git.RemoteRefs(remote)
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// The set of remote refs can be very large. Since CachedRemoteRefs only
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// returns branches, filter the remote refs and convert them to a set for
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// faster lookups in the skip calculation loop.
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actualRemoteBranchRefs := tools.NewStringSet()
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for _, ref := range actualRemoteRefs {
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if ref.Type == git.RefTypeRemoteBranch {
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actualRemoteBranchRefs.Add(ref.Name)
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}
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}
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// Only check for missing refs on remote; if the ref is different it has moved
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// forward probably, and if not and the ref has changed to a non-descendant
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// (force push) then that will cause a re-evaluation in a subsequent command.
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var skippedRefs []string
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for _, cachedRef := range cachedRemoteRefs {
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if actualRemoteBranchRefs.Contains(cachedRef.Name) {
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skippedRefs = append(skippedRefs, "^"+cachedRef.Sha)
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}
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}
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return skippedRefs
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}
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