snapuserd: Rename UserSnapshotDmUserHandler to HandlerThread.

This makes it easier to type, mostly, but clarifies that it's really
just a holder object for a SnapshotHandler, and HandlerHolder would
look too odd.

Bug: 269361087
Test: snapuserd builds
Change-Id: I18aad4a58814f1e14d71cdabdd7b5ef137bd24b5
diff --git a/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_server.cpp b/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_server.cpp
index d437d32..908729d 100644
--- a/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_server.cpp
+++ b/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_server.cpp
@@ -101,7 +101,7 @@
     JoinAllThreads();
 }
 
-UserSnapshotDmUserHandler::UserSnapshotDmUserHandler(std::shared_ptr<SnapshotHandler> snapuserd)
+HandlerThread::HandlerThread(std::shared_ptr<SnapshotHandler> snapuserd)
     : snapuserd_(snapuserd), misc_name_(snapuserd_->GetMiscName()) {}
 
 bool UserSnapshotServer::Sendmsg(android::base::borrowed_fd fd, const std::string& msg) {
@@ -307,7 +307,7 @@
     }
 }
 
-void UserSnapshotServer::RunThread(std::shared_ptr<UserSnapshotDmUserHandler> handler) {
+void UserSnapshotServer::RunThread(std::shared_ptr<HandlerThread> handler) {
     LOG(INFO) << "Entering thread for handler: " << handler->misc_name();
 
     if (!handler->snapuserd()->Start()) {
@@ -428,7 +428,7 @@
 
 void UserSnapshotServer::JoinAllThreads() {
     // Acquire the thread list within the lock.
-    std::vector<std::shared_ptr<UserSnapshotDmUserHandler>> dm_users;
+    std::vector<std::shared_ptr<HandlerThread>> dm_users;
     {
         std::lock_guard<std::mutex> guard(lock_);
         dm_users = std::move(dm_users_);
@@ -483,9 +483,10 @@
     SetTerminating();
 }
 
-std::shared_ptr<UserSnapshotDmUserHandler> UserSnapshotServer::AddHandler(
-        const std::string& misc_name, const std::string& cow_device_path,
-        const std::string& backing_device, const std::string& base_path_merge) {
+std::shared_ptr<HandlerThread> UserSnapshotServer::AddHandler(const std::string& misc_name,
+                                                              const std::string& cow_device_path,
+                                                              const std::string& backing_device,
+                                                              const std::string& base_path_merge) {
     auto snapuserd = std::make_shared<SnapshotHandler>(misc_name, cow_device_path, backing_device,
                                                        base_path_merge);
     if (!snapuserd->InitCowDevice()) {
@@ -501,7 +502,7 @@
         return nullptr;
     }
 
-    auto handler = std::make_shared<UserSnapshotDmUserHandler>(snapuserd);
+    auto handler = std::make_shared<HandlerThread>(snapuserd);
     {
         std::lock_guard<std::mutex> lock(lock_);
         if (FindHandler(&lock, misc_name) != dm_users_.end()) {
@@ -513,7 +514,7 @@
     return handler;
 }
 
-bool UserSnapshotServer::StartHandler(const std::shared_ptr<UserSnapshotDmUserHandler>& handler) {
+bool UserSnapshotServer::StartHandler(const std::shared_ptr<HandlerThread>& handler) {
     if (handler->snapuserd()->IsAttached()) {
         LOG(ERROR) << "Handler already attached";
         return false;
@@ -526,7 +527,7 @@
 }
 
 bool UserSnapshotServer::StartMerge(std::lock_guard<std::mutex>* proof_of_lock,
-                                    const std::shared_ptr<UserSnapshotDmUserHandler>& handler) {
+                                    const std::shared_ptr<HandlerThread>& handler) {
     CHECK(proof_of_lock);
 
     if (!handler->snapuserd()->IsAttached()) {
@@ -568,8 +569,7 @@
     }
 }
 
-std::string UserSnapshotServer::GetMergeStatus(
-        const std::shared_ptr<UserSnapshotDmUserHandler>& handler) {
+std::string UserSnapshotServer::GetMergeStatus(const std::shared_ptr<HandlerThread>& handler) {
     return handler->snapuserd()->GetMergeStatus();
 }
 
@@ -604,7 +604,7 @@
 }
 
 bool UserSnapshotServer::RemoveAndJoinHandler(const std::string& misc_name) {
-    std::shared_ptr<UserSnapshotDmUserHandler> handler;
+    std::shared_ptr<HandlerThread> handler;
     {
         std::lock_guard<std::mutex> lock(lock_);
 
diff --git a/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_server.h b/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_server.h
index c2af61f..12c3903 100644
--- a/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_server.h
+++ b/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_server.h
@@ -54,9 +54,9 @@
     INVALID,
 };
 
-class UserSnapshotDmUserHandler {
+class HandlerThread {
   public:
-    explicit UserSnapshotDmUserHandler(std::shared_ptr<SnapshotHandler> snapuserd);
+    explicit HandlerThread(std::shared_ptr<SnapshotHandler> snapuserd);
 
     void FreeResources() {
         // Each worker thread holds a reference to snapuserd.
@@ -99,9 +99,9 @@
 
     std::mutex lock_;
 
-    using HandlerList = std::vector<std::shared_ptr<UserSnapshotDmUserHandler>>;
+    using HandlerList = std::vector<std::shared_ptr<HandlerThread>>;
     HandlerList dm_users_;
-    std::queue<std::shared_ptr<UserSnapshotDmUserHandler>> merge_handlers_;
+    std::queue<std::shared_ptr<HandlerThread>> merge_handlers_;
 
     void AddWatchedFd(android::base::borrowed_fd fd, int events);
     void AcceptClient();
@@ -118,13 +118,13 @@
 
     bool IsTerminating() { return terminating_; }
 
-    void RunThread(std::shared_ptr<UserSnapshotDmUserHandler> handler);
+    void RunThread(std::shared_ptr<HandlerThread> handler);
     void MonitorMerge();
 
     void JoinAllThreads();
     bool StartWithSocket(bool start_listening);
 
-    // Find a UserSnapshotDmUserHandler within a lock.
+    // Find a HandlerThread within a lock.
     HandlerList::iterator FindHandler(std::lock_guard<std::mutex>* proof_of_lock,
                                       const std::string& misc_name);
 
@@ -143,14 +143,14 @@
     bool RunForSocketHandoff();
     bool WaitForSocket();
 
-    std::shared_ptr<UserSnapshotDmUserHandler> AddHandler(const std::string& misc_name,
-                                                          const std::string& cow_device_path,
-                                                          const std::string& backing_device,
-                                                          const std::string& base_path_merge);
-    bool StartHandler(const std::shared_ptr<UserSnapshotDmUserHandler>& handler);
+    std::shared_ptr<HandlerThread> AddHandler(const std::string& misc_name,
+                                              const std::string& cow_device_path,
+                                              const std::string& backing_device,
+                                              const std::string& base_path_merge);
+    bool StartHandler(const std::shared_ptr<HandlerThread>& handler);
     bool StartMerge(std::lock_guard<std::mutex>* proof_of_lock,
-                    const std::shared_ptr<UserSnapshotDmUserHandler>& handler);
-    std::string GetMergeStatus(const std::shared_ptr<UserSnapshotDmUserHandler>& handler);
+                    const std::shared_ptr<HandlerThread>& handler);
+    std::string GetMergeStatus(const std::shared_ptr<HandlerThread>& handler);
 
     void WakeupMonitorMergeThread();
     void SetTerminating() { terminating_ = true; }