chore: remove personal comments in file header (apache#1696)

There is no functional changes in this patch, just remove the comments at the
head of file, the comments look like:
```
/*
 * Description:
 *     What is this file about?
 *
 * Revision history:
 *     xxxx-xx-xx, author, first version
 *     xxxx-xx-xx, author, fix bug about xxx
 */
```

The description which are meaningful has been moved closer to the class declaration
it describes.

This patch also updates some links, for example, from `github.com/XiaoMi/pegasus/wiki`
to `pegasus.apache.org`, `github.com/XiaoMi/pegasus/issues` to
`github.com/apache/incubator-pegasus/issues`.

src/common/fs_manager.cpp

@@ -24,14 +24,6 @@
  * THE SOFTWARE.
  */
 
-/*
- * Description:
- *     fs_manager's implement: used to track the disk position for all the allocated replicas
- *
- * Revision history:
- *     2017-08-08: [email protected], first draft
- */
-
 #include "fs_manager.h"
 
 #include <algorithm>

src/common/fs_manager.h

@@ -84,6 +84,7 @@ struct dir_node
     void update_disk_stat();
 };
 
+// Track the data directories and replicas.
 class fs_manager
 {
 public:

src/common/gpid.h

@@ -23,6 +23,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */
+
 #pragma once
 
 #include <cstdint>

src/common/json_helper.h

@@ -23,6 +23,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */
+
 #pragma once
 
 #include <cctype>

src/common/replication_other_types.h

@@ -24,14 +24,6 @@
  * THE SOFTWARE.
  */
 
-/*
- * Description:
- *     What is this file about?
- *
- * Revision history:
- *     xxxx-xx-xx, author, first version
- *     xxxx-xx-xx, author, fix bug about xxx
- */
 #ifndef replication_OTHER_TYPES_H
 #define replication_OTHER_TYPES_H
 

src/failure_detector/failure_detector.h

@@ -24,41 +24,6 @@
  * THE SOFTWARE.
  */
 
-/*
- * Description:
- *     interface for a perfect failure detector
- *
- * Revision history:
- *     Mar., 2015, @imzhenyu (Zhenyu Guo), first version
- *     Dec., 2015, @shengofsun (Weijie Sun), make zlock preoteced,
- *                 give the subClasses flexibility
- *     xxxx-xx-xx, author, fix bug about xxx
- */
-
-/*
- * Notes on the failure detector:
- *
- * 1. Due to the fact that we can only check the liveness inside check-all-records call,
- *    which happens every "check_interval_seconds" seconds, worker may disconnect from master
- *    in the period earlier than the lease_seconds to ensure the perfect FD.
- *    In the worst case, workers may disconnect themselves
- *    after "lease"-"check_interval_seconds" seconds;
- *
- *    Similarily, master may claim a worker dead more slowly even the workers are dead
- *    for longer than grace_seconds. In the worst case, it will be
- *    "grace"+"check_interval_seconds" seconds.
- *
- * 2. In practice, your should set check_interval_seconds a small value for a fine-grained FD.
- *    For client, you may set it as 2 second as it usually connect to a small number of masters.
- *    For master, you may set it as 5 or 10 seconds.
- *
- * 3. We should always use dedicated thread pools for THREAD_POOL_FD,
- *    and set thread priority to being highest so as to minimize the performance
- *    interference with other workloads.
- *
- * 4. The lease_periods must be less than the grace_periods, as required by prefect FD.
- *
- */
 #pragma once
 
 #include <stdint.h>
@@ -106,6 +71,29 @@ class failure_detector_callback
     virtual void on_worker_connected(::dsn::rpc_address node) = 0;
 };
 
+// The interface for a perfect failure detector.
+//
+// Notes on the failure detector:
+//
+// 1. Due to the fact that we can only check the liveness inside check-all-records call,
+//    which happens every "check_interval_seconds" seconds, worker may disconnect from master
+//    in the period earlier than the lease_seconds to ensure the perfect FD.
+//    In the worst case, workers may disconnect themselves
+//    after "lease"-"check_interval_seconds" seconds;
+//
+//    Similarily, master may claim a worker dead more slowly even the workers are dead
+//    for longer than grace_seconds. In the worst case, it will be
+//    "grace"+"check_interval_seconds" seconds.
+//
+// 2. In practice, your should set check_interval_seconds a small value for a fine-grained FD.
+//    For client, you may set it as 2 second as it usually connect to a small number of masters.
+//    For master, you may set it as 5 or 10 seconds.
+//
+// 3. We should always use dedicated thread pools for THREAD_POOL_FD,
+//    and set thread priority to being highest so as to minimize the performance
+//    interference with other workloads.
+//
+// 4. The lease_periods must be less than the grace_periods, as required by prefect FD.
 class failure_detector : public failure_detector_service,
                          public failure_detector_client,
                          public failure_detector_callback

src/failure_detector/failure_detector_multimaster.cpp

@@ -24,15 +24,6 @@
  * THE SOFTWARE.
  */
 
-/*
- * Description:
- *     What is this file about?
- *
- * Revision history:
- *     xxxx-xx-xx, author, first version
- *     xxxx-xx-xx, author, fix bug about xxx
- */
-
 #include <stdint.h>
 #include <utility>
 

src/failure_detector/fd.client.h

@@ -24,15 +24,6 @@
  * THE SOFTWARE.
  */
 
-/*
- * Description:
- *     What is this file about?
- *
- * Revision history:
- *     xxxx-xx-xx, author, first version
- *     xxxx-xx-xx, author, fix bug about xxx
- */
-
 #pragma once
 #include "fd.code.definition.h"
 #include <iostream>

src/failure_detector/fd.server.h

@@ -24,15 +24,6 @@
  * THE SOFTWARE.
  */
 
-/*
- * Description:
- *     What is this file about?
- *
- * Revision history:
- *     xxxx-xx-xx, author, first version
- *     xxxx-xx-xx, author, fix bug about xxx
- */
-
 #pragma once
 #include "fd.code.definition.h"
 #include <iostream>

src/meta/distributed_lock_service_simple.cpp

@@ -24,15 +24,6 @@
  * THE SOFTWARE.
  */
 
-/*
- * Description:
- *     a simple version of distributed lock service for development
- *
- * Revision history:
- *     2015-11-04, @imzhenyu ([email protected]), first version
- *     xxxx-xx-xx, author, fix bug about xxx
- */
-
 #include <chrono>
 
 #include "common/replication.codes.h"

src/meta/distributed_lock_service_simple.h

@@ -24,15 +24,6 @@
  * THE SOFTWARE.
  */
 
-/*
- * Description:
- *     a simple version of distributed lock service for development
- *
- * Revision history:
- *     2015-11-04, @imzhenyu ([email protected]), first version
- *     xxxx-xx-xx, author, fix bug about xxx
- */
-
 #pragma once
 
 #include <stdint.h>
@@ -53,7 +44,9 @@
 
 namespace dsn {
 namespace dist {
-// Only for test purpose.
+
+// A simple version of distributed lock service.
+// NOTE: Only for test purpose.
 class distributed_lock_service_simple : public distributed_lock_service
 {
 public:

src/meta/greedy_load_balancer.h

@@ -24,14 +24,6 @@
  * THE SOFTWARE.
  */
 
-/*
- * Description:
- *     A greedy load balancer based on Dijkstra & Ford-Fulkerson
- *
- * Revision history:
- *     2016-02-03, Weijie Sun, first version
- */
-
 #pragma once
 
 #include <memory>
@@ -51,6 +43,7 @@ namespace replication {
 class load_balance_policy;
 class meta_service;
 
+// A greedy load balancer based on Dijkstra & Ford-Fulkerson.
 class greedy_load_balancer : public server_load_balancer
 {
 public:

src/meta/meta_data.cpp

@@ -24,14 +24,6 @@
  * THE SOFTWARE.
  */
 
-/*
- * Description:
- *     the meta server's date structure, impl file
- *
- * Revision history:
- *     2016-04-25, Weijie Sun(sunweijie at xiaomi.com), first version
- *     xxxx-xx-xx, author, fix bug about xxx
- */
 #include <boost/lexical_cast.hpp>
 #include <cstdint>
 

src/meta/meta_data.h

@@ -24,14 +24,6 @@
  * THE SOFTWARE.
  */
 
-/*
- * Description:
- *     the meta server's date structure
- *
- * Revision history:
- *     2016-04-25, Weijie Sun(sunweijie at xiaomi.com), first version
- *     xxxx-xx-xx, author, fix bug about xxx
- */
 #pragma once
 
 #include <stdint.h>

src/meta/meta_options.cpp

@@ -24,14 +24,6 @@
  * THE SOFTWARE.
  */
 
-/*
- * Description:
- *     the meta server's options, impl file
- *
- * Revision history:
- *     2016-04-25, Weijie Sun(sunweijie at xiaomi.com), first version
- *     xxxx-xx-xx, author, fix bug about xxx
- */
 #include "meta_options.h"
 
 #include <stddef.h>

src/meta/meta_options.h

@@ -24,14 +24,6 @@
  * THE SOFTWARE.
  */
 
-/*
- * Description:
- *     the meta server's options
- *
- * Revision history:
- *     2016-04-25, Weijie Sun(sunweijie at xiaomi.com), first version
- *     xxxx-xx-xx, author, fix bug about xxx
- */
 #pragma once
 
 #include <string>
@@ -49,6 +41,7 @@ class fd_suboptions
     std::vector<std::string> distributed_lock_service_args;
 };
 
+// The meta server's options.
 class meta_options
 {
 public:

src/meta/meta_service.h

@@ -24,15 +24,6 @@
  * THE SOFTWARE.
  */
 
-/*
- * Description:
- *     meta server service for EON (rDSN layer 2)
- *
- * Revision history:
- *     2015-03-09, @imzhenyu (Zhenyu Guo), first version
- *     xxxx-xx-xx, author, fix bug about xxx
- */
-
 #pragma once
 
 #include <fmt/core.h>
@@ -132,6 +123,7 @@ enum class meta_leader_state : int
     kNotLeaderAndCannotForwardRpc, // meta isn't leader, and rpc-msg can't forward to others
 };
 
+// Meta server service for EON (rDSN layer 2).
 class meta_service : public serverlet<meta_service>
 {
 public:

src/meta/meta_service_app.h

@@ -23,6 +23,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */
+
 #pragma once
 
 #include <memory>

src/meta/meta_state_service.h

@@ -24,23 +24,6 @@
  * THE SOFTWARE.
  */
 
-/*
- * Description:
- *     interface of the reliable meta state service
- *     it is usually for storing meta state of dist systems, such as membership
- *
- * Revision history:
- *     2015-10-28, Weijie Sun, first version
- *     2015-11-05, @imzhenyu (Zhenyu Guo), adjust the interface, so that
- *                (1) return task_ptr/tracker for callers to cancel or wait;
- *                (2) add factory for provider registration;
- *                (3) add cb_code parameter, then users can specify where the callback
- *                    should be executed
- *     2015-11-06, @imzhenyu (Zhenyu Guo), add watch/unwatch API
- *     2015-12-28, @shengofsun (Weijie SUn), add transaction api
- *     xxxx-xx-xx, author, fix bug about xxx
- */
-
 #pragma once
 
 #include <functional>
@@ -68,6 +51,8 @@ typedef std::function<void(error_code ec, const std::vector<std::string> &ret_st
 typedef future_task<error_code, std::vector<std::string>> err_stringv_future;
 typedef dsn::ref_ptr<err_stringv_future> err_stringv_future_ptr;
 
+// The interface of the reliable meta state service.
+// It is usually for storing meta state of dist systems, such as membership.
 class meta_state_service
 {
 public:

src/meta/meta_state_service_simple.h

@@ -24,15 +24,6 @@
  * THE SOFTWARE.
  */
 
-/*
- * Description:
- *     a simple version of meta state service for development
- *
- * Revision history:
- *     2015-11-03, @imzhenyu ([email protected]), setup the sketch
- *     2015-11-11, Tianyi WANG, first version done
- */
-
 #include <stddef.h>
 #include <stdint.h>
 #include <functional>
@@ -66,7 +57,8 @@ DEFINE_TASK_CODE_AIO(LPC_META_STATE_SERVICE_SIMPLE_INTERNAL,
                      TASK_PRIORITY_HIGH,
                      THREAD_POOL_DEFAULT);
 
-// Only for test purpose.
+// A simple version of meta state service.
+// NOTE: Only for test purpose.
 class meta_state_service_simple : public meta_state_service
 {
 public: