Add functions in FUSE integration test to get metrics from FUSE server

This commit adds 3 utility functions to ensure all received requests
and preset responses are consumed.

1. Get number of unconsumed requests (received by the FUSE server but
   not consumed by the testing thread).
2. Get number of unsent responses (set by the testing thread but not
   processed by the FUSE server).
3. Get total bytes of the received requests (to ensure some operations
   don't trigger FUSE requests).

Fixes #3607

1 files changed, 52 insertions, 6 deletions

diff --git a/test/fuse/linux/fuse_base.cc b/test/fuse/linux/fuse_base.cc
index b7d8b2a1f..b1897cf88 100644
--- a/test/fuse/linux/fuse_base.cc
+++ b/test/fuse/linux/fuse_base.cc
@@ -38,7 +38,11 @@ void FuseTest::SetUp() {
   SetUpFuseServer();
 }
 
-void FuseTest::TearDown() { UnmountFuse(); }
+void FuseTest::TearDown() {
+  EXPECT_EQ(GetServerNumUnconsumedRequests(), 0);
+  EXPECT_EQ(GetServerNumUnsentResponses(), 0);
+  UnmountFuse();
+}
 
 // Sends 3 parts of data to the FUSE server:
 //   1. The `kSetResponse` command
@@ -63,10 +67,10 @@ void FuseTest::SetServerResponse(uint32_t opcode,
 // Waits for the FUSE server to finish its blocking job and check if it
 // completes without errors.
 void FuseTest::WaitServerComplete() {
-  char success;
+  uint32_t success;
   EXPECT_THAT(RetryEINTR(read)(sock_[0], &success, sizeof(success)),
               SyscallSucceedsWithValue(sizeof(success)));
-  EXPECT_EQ(success, static_cast<char>(1));
+  ASSERT_EQ(success, 1);
 }
 
 // Sends the `kGetRequest` command to the FUSE server, then reads the next
@@ -83,6 +87,35 @@ void FuseTest::GetServerActualRequest(std::vector<struct iovec>& iovecs) {
   WaitServerComplete();
 }
 
+// Sends a FuseTestCmd command to the FUSE server, reads from the socket, and
+// returns the corresponding data.
+uint32_t FuseTest::GetServerData(uint32_t cmd) {
+  uint32_t data;
+  EXPECT_THAT(RetryEINTR(write)(sock_[0], &cmd, sizeof(cmd)),
+              SyscallSucceedsWithValue(sizeof(cmd)));
+
+  EXPECT_THAT(RetryEINTR(read)(sock_[0], &data, sizeof(data)),
+              SyscallSucceedsWithValue(sizeof(data)));
+
+  WaitServerComplete();
+  return data;
+}
+
+uint32_t FuseTest::GetServerNumUnconsumedRequests() {
+  return GetServerData(
+      static_cast<uint32_t>(FuseTestCmd::kGetNumUnconsumedRequests));
+}
+
+uint32_t FuseTest::GetServerNumUnsentResponses() {
+  return GetServerData(
+      static_cast<uint32_t>(FuseTestCmd::kGetNumUnsentResponses));
+}
+
+uint32_t FuseTest::GetServerTotalReceivedBytes() {
+  return GetServerData(
+      static_cast<uint32_t>(FuseTestCmd::kGetTotalReceivedBytes));
+}
+
 void FuseTest::MountFuse() {
   EXPECT_THAT(dev_fd_ = open("/dev/fuse", O_RDWR), SyscallSucceeds());
 
@@ -141,9 +174,8 @@ void FuseTest::ServerReceiveResponse() {
 
 // Writes 1 byte of success indicator through socket.
 void FuseTest::ServerCompleteWith(bool success) {
-  char data = static_cast<char>(success);
-  EXPECT_THAT(RetryEINTR(write)(sock_[1], &data, sizeof(data)),
-              SyscallSucceedsWithValue(sizeof(data)));
+  uint32_t data = success ? 1 : 0;
+  ServerSendData(data);
 }
 
 // ServerFuseLoop is the implementation of the fake FUSE server. Monitors 2
@@ -205,6 +237,11 @@ void FuseTest::SetUpFuseServer() {
   _exit(0);
 }
 
+void FuseTest::ServerSendData(uint32_t data) {
+  EXPECT_THAT(RetryEINTR(write)(sock_[1], &data, sizeof(data)),
+              SyscallSucceedsWithValue(sizeof(data)));
+}
+
 // Reads FuseTestCmd sent from testing thread and routes to correct handler.
 // Since each command should be a blocking operation, a `ServerCompleteWith()`
 // is required after the switch keyword.
@@ -220,6 +257,15 @@ void FuseTest::ServerHandleCommand() {
     case FuseTestCmd::kGetRequest:
       ServerSendReceivedRequest();
       break;
+    case FuseTestCmd::kGetTotalReceivedBytes:
+      ServerSendData(static_cast<uint32_t>(requests_.UsedBytes()));
+      break;
+    case FuseTestCmd::kGetNumUnconsumedRequests:
+      ServerSendData(static_cast<uint32_t>(requests_.RemainingBlocks()));
+      break;
+    case FuseTestCmd::kGetNumUnsentResponses:
+      ServerSendData(static_cast<uint32_t>(responses_.RemainingBlocks()));
+      break;
     default:
       FAIL() << "Unknown FuseTestCmd " << cmd;
       break;