Add initial implementation of priority queue, uses container/heap

pkg/storage/pq/task.go

@@ -0,0 +1,38 @@
+/*
+ * Minimalist Object Storage, (C) 2015 Minio, Inc.
+ *
+ * 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 pq
+
+// Task container for any generic tasks
+type Task struct {
+	job      func() error
+	priority int
+}
+
+// GetPriority get current task priority
+func (t Task) GetPriority() int {
+	return t.priority
+}
+
+// UpdatePriority update current task priority
+func (t Task) UpdatePriority(p int) {
+	t.priority = p
+}
+
+// Execute execute current task
+func (t Task) Execute() error {
+	return t.job()
+}