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authorAndrei Vagin <avagin@google.com>2020-03-06 21:12:32 -0800
committerGitHub <noreply@github.com>2020-03-06 21:12:32 -0800
commitbf87da89d3c43555fd57e8f1d7aed21b6da78de4 (patch)
tree744ba15a2f663d64d56bf1c70bdfe4096f6a1af9 /pkg/pool
parent89957c6c87b5ad5c7bac68f93d9472388db57702 (diff)
parentddfc7239be94fa9711df877a66a9718aabff8b96 (diff)
Merge branch 'master' into pr_lazy_fpsimd_2
Diffstat (limited to 'pkg/pool')
-rw-r--r--pkg/pool/BUILD25
-rw-r--r--pkg/pool/pool.go66
-rw-r--r--pkg/pool/pool_test.go64
3 files changed, 155 insertions, 0 deletions
diff --git a/pkg/pool/BUILD b/pkg/pool/BUILD
new file mode 100644
index 000000000..7b1c6b75b
--- /dev/null
+++ b/pkg/pool/BUILD
@@ -0,0 +1,25 @@
+load("//tools:defs.bzl", "go_library", "go_test")
+
+package(
+ default_visibility = ["//visibility:public"],
+ licenses = ["notice"],
+)
+
+go_library(
+ name = "pool",
+ srcs = [
+ "pool.go",
+ ],
+ deps = [
+ "//pkg/sync",
+ ],
+)
+
+go_test(
+ name = "pool_test",
+ size = "small",
+ srcs = [
+ "pool_test.go",
+ ],
+ library = ":pool",
+)
diff --git a/pkg/pool/pool.go b/pkg/pool/pool.go
new file mode 100644
index 000000000..a1b2e0cfe
--- /dev/null
+++ b/pkg/pool/pool.go
@@ -0,0 +1,66 @@
+// Copyright 2018 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package pool
+
+import (
+ "gvisor.dev/gvisor/pkg/sync"
+)
+
+// Pool is a simple allocator.
+type Pool struct {
+ mu sync.Mutex
+
+ // cache is the set of returned values.
+ cache []uint64
+
+ // Start is the starting value (if needed).
+ Start uint64
+
+ // max is the current maximum issued.
+ max uint64
+
+ // Limit is the upper limit.
+ Limit uint64
+}
+
+// Get gets a value from the pool.
+func (p *Pool) Get() (uint64, bool) {
+ p.mu.Lock()
+ defer p.mu.Unlock()
+
+ // Anything cached?
+ if len(p.cache) > 0 {
+ v := p.cache[len(p.cache)-1]
+ p.cache = p.cache[:len(p.cache)-1]
+ return v, true
+ }
+
+ // Over the limit?
+ if p.Start == p.Limit {
+ return 0, false
+ }
+
+ // Generate a new value.
+ v := p.Start
+ p.Start++
+ return v, true
+}
+
+// Put returns a value to the pool.
+func (p *Pool) Put(v uint64) {
+ p.mu.Lock()
+ p.cache = append(p.cache, v)
+ p.mu.Unlock()
+}
diff --git a/pkg/pool/pool_test.go b/pkg/pool/pool_test.go
new file mode 100644
index 000000000..d928439c1
--- /dev/null
+++ b/pkg/pool/pool_test.go
@@ -0,0 +1,64 @@
+// Copyright 2018 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package pool
+
+import (
+ "testing"
+)
+
+func TestPoolUnique(t *testing.T) {
+ p := Pool{Start: 1, Limit: 3}
+ got := make(map[uint64]bool)
+
+ for {
+ n, ok := p.Get()
+ if !ok {
+ break
+ }
+
+ // Check unique.
+ if _, ok := got[n]; ok {
+ t.Errorf("pool spit out %v multiple times", n)
+ }
+
+ // Record.
+ got[n] = true
+ }
+}
+
+func TestExausted(t *testing.T) {
+ p := Pool{Start: 1, Limit: 500}
+ for i := 0; i < 499; i++ {
+ _, ok := p.Get()
+ if !ok {
+ t.Fatalf("pool exhausted before 499 items")
+ }
+ }
+
+ _, ok := p.Get()
+ if ok {
+ t.Errorf("pool not exhausted when it should be")
+ }
+}
+
+func TestPoolRecycle(t *testing.T) {
+ p := Pool{Start: 1, Limit: 500}
+ n1, _ := p.Get()
+ p.Put(n1)
+ n2, _ := p.Get()
+ if n1 != n2 {
+ t.Errorf("pool not recycling items")
+ }
+}