summaryrefslogtreecommitdiff
path: root/vendor/golang.org/x/sync
diff options
context:
space:
mode:
Diffstat (limited to 'vendor/golang.org/x/sync')
-rw-r--r--vendor/golang.org/x/sync/LICENSE27
-rw-r--r--vendor/golang.org/x/sync/PATENTS22
-rw-r--r--vendor/golang.org/x/sync/README.md18
-rw-r--r--vendor/golang.org/x/sync/semaphore/semaphore.go127
4 files changed, 194 insertions, 0 deletions
diff --git a/vendor/golang.org/x/sync/LICENSE b/vendor/golang.org/x/sync/LICENSE
new file mode 100644
index 000000000..6a66aea5e
--- /dev/null
+++ b/vendor/golang.org/x/sync/LICENSE
@@ -0,0 +1,27 @@
+Copyright (c) 2009 The Go Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+ * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+ * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+ * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/vendor/golang.org/x/sync/PATENTS b/vendor/golang.org/x/sync/PATENTS
new file mode 100644
index 000000000..733099041
--- /dev/null
+++ b/vendor/golang.org/x/sync/PATENTS
@@ -0,0 +1,22 @@
+Additional IP Rights Grant (Patents)
+
+"This implementation" means the copyrightable works distributed by
+Google as part of the Go project.
+
+Google hereby grants to You a perpetual, worldwide, non-exclusive,
+no-charge, royalty-free, irrevocable (except as stated in this section)
+patent license to make, have made, use, offer to sell, sell, import,
+transfer and otherwise run, modify and propagate the contents of this
+implementation of Go, where such license applies only to those patent
+claims, both currently owned or controlled by Google and acquired in
+the future, licensable by Google that are necessarily infringed by this
+implementation of Go. This grant does not include claims that would be
+infringed only as a consequence of further modification of this
+implementation. If you or your agent or exclusive licensee institute or
+order or agree to the institution of patent litigation against any
+entity (including a cross-claim or counterclaim in a lawsuit) alleging
+that this implementation of Go or any code incorporated within this
+implementation of Go constitutes direct or contributory patent
+infringement, or inducement of patent infringement, then any patent
+rights granted to you under this License for this implementation of Go
+shall terminate as of the date such litigation is filed.
diff --git a/vendor/golang.org/x/sync/README.md b/vendor/golang.org/x/sync/README.md
new file mode 100644
index 000000000..1f8436cc9
--- /dev/null
+++ b/vendor/golang.org/x/sync/README.md
@@ -0,0 +1,18 @@
+# Go Sync
+
+This repository provides Go concurrency primitives in addition to the
+ones provided by the language and "sync" and "sync/atomic" packages.
+
+## Download/Install
+
+The easiest way to install is to run `go get -u golang.org/x/sync`. You can
+also manually git clone the repository to `$GOPATH/src/golang.org/x/sync`.
+
+## Report Issues / Send Patches
+
+This repository uses Gerrit for code changes. To learn how to submit changes to
+this repository, see https://golang.org/doc/contribute.html.
+
+The main issue tracker for the sync repository is located at
+https://github.com/golang/go/issues. Prefix your issue with "x/sync:" in the
+subject line, so it is easy to find.
diff --git a/vendor/golang.org/x/sync/semaphore/semaphore.go b/vendor/golang.org/x/sync/semaphore/semaphore.go
new file mode 100644
index 000000000..ac53e733e
--- /dev/null
+++ b/vendor/golang.org/x/sync/semaphore/semaphore.go
@@ -0,0 +1,127 @@
+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package semaphore provides a weighted semaphore implementation.
+package semaphore // import "golang.org/x/sync/semaphore"
+
+import (
+ "container/list"
+ "context"
+ "sync"
+)
+
+type waiter struct {
+ n int64
+ ready chan<- struct{} // Closed when semaphore acquired.
+}
+
+// NewWeighted creates a new weighted semaphore with the given
+// maximum combined weight for concurrent access.
+func NewWeighted(n int64) *Weighted {
+ w := &Weighted{size: n}
+ return w
+}
+
+// Weighted provides a way to bound concurrent access to a resource.
+// The callers can request access with a given weight.
+type Weighted struct {
+ size int64
+ cur int64
+ mu sync.Mutex
+ waiters list.List
+}
+
+// Acquire acquires the semaphore with a weight of n, blocking until resources
+// are available or ctx is done. On success, returns nil. On failure, returns
+// ctx.Err() and leaves the semaphore unchanged.
+//
+// If ctx is already done, Acquire may still succeed without blocking.
+func (s *Weighted) Acquire(ctx context.Context, n int64) error {
+ s.mu.Lock()
+ if s.size-s.cur >= n && s.waiters.Len() == 0 {
+ s.cur += n
+ s.mu.Unlock()
+ return nil
+ }
+
+ if n > s.size {
+ // Don't make other Acquire calls block on one that's doomed to fail.
+ s.mu.Unlock()
+ <-ctx.Done()
+ return ctx.Err()
+ }
+
+ ready := make(chan struct{})
+ w := waiter{n: n, ready: ready}
+ elem := s.waiters.PushBack(w)
+ s.mu.Unlock()
+
+ select {
+ case <-ctx.Done():
+ err := ctx.Err()
+ s.mu.Lock()
+ select {
+ case <-ready:
+ // Acquired the semaphore after we were canceled. Rather than trying to
+ // fix up the queue, just pretend we didn't notice the cancelation.
+ err = nil
+ default:
+ s.waiters.Remove(elem)
+ }
+ s.mu.Unlock()
+ return err
+
+ case <-ready:
+ return nil
+ }
+}
+
+// TryAcquire acquires the semaphore with a weight of n without blocking.
+// On success, returns true. On failure, returns false and leaves the semaphore unchanged.
+func (s *Weighted) TryAcquire(n int64) bool {
+ s.mu.Lock()
+ success := s.size-s.cur >= n && s.waiters.Len() == 0
+ if success {
+ s.cur += n
+ }
+ s.mu.Unlock()
+ return success
+}
+
+// Release releases the semaphore with a weight of n.
+func (s *Weighted) Release(n int64) {
+ s.mu.Lock()
+ s.cur -= n
+ if s.cur < 0 {
+ s.mu.Unlock()
+ panic("semaphore: bad release")
+ }
+ for {
+ next := s.waiters.Front()
+ if next == nil {
+ break // No more waiters blocked.
+ }
+
+ w := next.Value.(waiter)
+ if s.size-s.cur < w.n {
+ // Not enough tokens for the next waiter. We could keep going (to try to
+ // find a waiter with a smaller request), but under load that could cause
+ // starvation for large requests; instead, we leave all remaining waiters
+ // blocked.
+ //
+ // Consider a semaphore used as a read-write lock, with N tokens, N
+ // readers, and one writer. Each reader can Acquire(1) to obtain a read
+ // lock. The writer can Acquire(N) to obtain a write lock, excluding all
+ // of the readers. If we allow the readers to jump ahead in the queue,
+ // the writer will starve — there is always one token available for every
+ // reader.
+ break
+ }
+
+ s.cur += w.n
+ s.waiters.Remove(next)
+ close(w.ready)
+ }
+ s.mu.Unlock()
+}