Implement list, clear locks REST API w/ pkg/madmin support (#3491)

* Filter lock info based on bucket, prefix and time since lock was held
* Implement list and clear locks REST API
* madmin: Add list and clear locks API
* locks: Clear locks matching bucket, prefix, relTime.
* Gather lock information across nodes for both list and clear locks admin REST API.
* docs: Add lock API to management APIs

pkg/madmin/lock-commands.go

@@ -0,0 +1,151 @@
+/*
+ * Minio Cloud Storage, (C) 2016 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 madmin
+
+import (
+	"encoding/json"
+	"errors"
+	"io"
+	"io/ioutil"
+	"net/http"
+	"net/url"
+	"time"
+)
+
+type statusType string
+
+const (
+	runningStatus statusType = "Running"
+	blockedStatus statusType = "Blocked"
+)
+
+type lockType string
+
+const (
+	debugRLockStr lockType = "RLock"
+	debugWLockStr lockType = "WLock"
+)
+
+// OpsLockState - represents lock specific details.
+type OpsLockState struct {
+	OperationID string        `json:"opsID"`          // String containing operation ID.
+	LockSource  string        `json:"lockSource"`     // Operation type (GetObject, PutObject...)
+	LockType    lockType      `json:"lockType"`       // Lock type (RLock, WLock)
+	Status      statusType    `json:"status"`         // Status can be Running/Ready/Blocked.
+	Since       time.Time     `json:"statusSince"`    // Time when the lock was initially held.
+	Duration    time.Duration `json:"statusDuration"` // Duration since the lock was held.
+}
+
+// VolumeLockInfo - represents summary and individual lock details of all
+// locks held on a given bucket, object.
+type VolumeLockInfo struct {
+	Bucket string `json:"bucket"`
+	Object string `json:"object"`
+	// All locks blocked + running for given <volume,path> pair.
+	LocksOnObject int64 `json:"locksOnObject"`
+	// Count of operations which has successfully acquired the lock
+	// but hasn't unlocked yet( operation in progress).
+	LocksAcquiredOnObject int64 `json:"locksAcquiredOnObject"`
+	// Count of operations which are blocked waiting for the lock
+	// to be released.
+	TotalBlockedLocks int64 `json:"locksBlockedOnObject"`
+	// State information containing state of the locks for all operations
+	// on given <volume,path> pair.
+	LockDetailsOnObject []OpsLockState `json:"lockDetailsOnObject"`
+}
+
+// getLockInfos - unmarshal []VolumeLockInfo from a reader.
+func getLockInfos(body io.Reader) ([]VolumeLockInfo, error) {
+	respBytes, err := ioutil.ReadAll(body)
+	if err != nil {
+		return nil, err
+	}
+
+	var lockInfos []VolumeLockInfo
+
+	err = json.Unmarshal(respBytes, &lockInfos)
+	if err != nil {
+		return nil, err
+	}
+
+	return lockInfos, nil
+}
+
+// ListLocks - Calls List Locks Management API to fetch locks matching
+// bucket, prefix and held before the duration supplied.
+func (adm *AdminClient) ListLocks(bucket, prefix string, olderThan time.Duration) ([]VolumeLockInfo, error) {
+	queryVal := make(url.Values)
+	queryVal.Set("lock", "")
+	queryVal.Set("bucket", bucket)
+	queryVal.Set("prefix", prefix)
+	queryVal.Set("older-than", olderThan.String())
+
+	hdrs := make(http.Header)
+	hdrs.Set(minioAdminOpHeader, "list")
+
+	reqData := requestData{
+		queryValues:   queryVal,
+		customHeaders: hdrs,
+	}
+
+	// Execute GET on /?lock to list locks.
+	resp, err := adm.executeMethod("GET", reqData)
+
+	defer closeResponse(resp)
+	if err != nil {
+		return nil, err
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, errors.New("Got HTTP Status: " + resp.Status)
+	}
+
+	return getLockInfos(resp.Body)
+}
+
+// ClearLocks - Calls Clear Locks Management API to clear locks held
+// on bucket, matching prefix older than duration supplied.
+func (adm *AdminClient) ClearLocks(bucket, prefix string, olderThan time.Duration) ([]VolumeLockInfo, error) {
+	queryVal := make(url.Values)
+	queryVal.Set("lock", "")
+	queryVal.Set("bucket", bucket)
+	queryVal.Set("prefix", prefix)
+	queryVal.Set("older-than", olderThan.String())
+
+	hdrs := make(http.Header)
+	hdrs.Set(minioAdminOpHeader, "clear")
+
+	reqData := requestData{
+		queryValues:   queryVal,
+		customHeaders: hdrs,
+	}
+
+	// Execute POST on /?lock to clear locks.
+	resp, err := adm.executeMethod("POST", reqData)
+
+	defer closeResponse(resp)
+	if err != nil {
+		return nil, err
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, errors.New("Got HTTP Status: " + resp.Status)
+	}
+
+	return getLockInfos(resp.Body)
+}