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https://github.com/golang/go
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d87e9bbada
We need to limit the concurrent file reads to prevent `too many open file` errors. The first attempt to solve this was done in change 189437, but this change turned out to be incorrect. So this change reverts the changes made in change 189437 and instead adds an new semaphore around the `nativeFileHandle.Read` method. The limit is currently set to half of the lowest open file system limit of *nix, Windows and MacOS system (their respective limits are 1024, 16384, and 256). Change-Id: I27d741e3a3c36eb11bfa7457575f5d5831c06ad7 Reviewed-on: https://go-review.googlesource.com/c/tools/+/190417 Reviewed-by: Ian Cottrell <iancottrell@google.com> Run-TryBot: Ian Cottrell <iancottrell@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org>
69 lines
1.8 KiB
Go
69 lines
1.8 KiB
Go
// Copyright 2019 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package cache
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import (
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"context"
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"io/ioutil"
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"os"
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"golang.org/x/tools/internal/lsp/source"
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"golang.org/x/tools/internal/lsp/telemetry"
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"golang.org/x/tools/internal/lsp/telemetry/trace"
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"golang.org/x/tools/internal/span"
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)
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// ioLimit limits the number of parallel file reads per process.
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var ioLimit = make(chan struct{}, 128)
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// nativeFileSystem implements FileSystem reading from the normal os file system.
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type nativeFileSystem struct{}
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// nativeFileHandle implements FileHandle for nativeFileSystem
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type nativeFileHandle struct {
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fs *nativeFileSystem
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identity source.FileIdentity
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}
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func (fs *nativeFileSystem) GetFile(uri span.URI) source.FileHandle {
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version := "DOES NOT EXIST"
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if fi, err := os.Stat(uri.Filename()); err == nil {
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version = fi.ModTime().String()
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}
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return &nativeFileHandle{
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fs: fs,
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identity: source.FileIdentity{
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URI: uri,
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Version: version,
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},
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}
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}
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func (h *nativeFileHandle) FileSystem() source.FileSystem {
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return h.fs
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}
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func (h *nativeFileHandle) Identity() source.FileIdentity {
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return h.identity
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}
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func (h *nativeFileHandle) Kind() source.FileKind {
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// TODO: How should we determine the file kind?
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return source.Go
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}
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func (h *nativeFileHandle) Read(ctx context.Context) ([]byte, string, error) {
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ctx, done := trace.StartSpan(ctx, "cache.nativeFileHandle.Read", telemetry.File.Of(h.identity.URI.Filename()))
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defer done()
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ioLimit <- struct{}{}
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defer func() { <-ioLimit }()
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//TODO: this should fail if the version is not the same as the handle
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data, err := ioutil.ReadFile(h.identity.URI.Filename())
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if err != nil {
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return nil, "", err
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}
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return data, hashContents(data), nil
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}
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