From d0ecb46d646e0f74f8f019307f721496781331ba Mon Sep 17 00:00:00 2001
From: John Knox <jknox@fb.com>
Date: Mon, 9 Jul 2018 07:46:09 -0700
Subject: [PATCH] Skip initialisation if not running in own thread

Summary:
One design goal of sonar is to never cause the host app to crash or hang.
For this reason, we do all heavy work in a background thread.
If we detect that it's not running in it's own thread, just return so we don't hold up the caller.

Reviewed By: danielbuechele

Differential Revision: D8767288

fbshipit-source-id: e146cc2cfe5c3e62d12f527ff79f24c74873d4ff
---
 xplat/Sonar/SonarWebSocketImpl.cpp | 10 ++++++++++
 xplat/Sonar/SonarWebSocketImpl.h   |  1 +
 2 files changed, 11 insertions(+)

diff --git a/xplat/Sonar/SonarWebSocketImpl.cpp b/xplat/Sonar/SonarWebSocketImpl.cpp
index b10de40a3e7..021d85744fd 100644
--- a/xplat/Sonar/SonarWebSocketImpl.cpp
+++ b/xplat/Sonar/SonarWebSocketImpl.cpp
@@ -33,6 +33,8 @@
 #define SONAR_CA_FILE_NAME "sonarCA.crt"
 #define CLIENT_CERT_FILE_NAME "device.crt"
 #define PRIVATE_KEY_FILE "privateKey.pem"
+#define WRONG_THREAD_EXIT_MSG \
+  "ERROR: Aborting sonar initialization because it's not running in the sonar thread."
 
 static constexpr int reconnectIntervalSeconds = 2;
 static constexpr int connectionKeepaliveSeconds = 10;
@@ -104,6 +106,10 @@ void SonarWebSocketImpl::start() {
 }
 
 void SonarWebSocketImpl::startSync() {
+  if (!isRunningInOwnThread()) {
+    SONAR_LOG(WRONG_THREAD_EXIT_MSG);
+    return;
+  }
   if (isOpen()) {
     SONAR_LOG("Already connected");
     return;
@@ -289,6 +295,10 @@ bool SonarWebSocketImpl::ensureSonarDirExists() {
   }
 }
 
+bool SonarWebSocketImpl::isRunningInOwnThread() {
+  return sonarEventBase_->isInEventBaseThread();
+}
+
 bool fileExists(std::string fileName) {
   struct stat buffer;
   return stat(fileName.c_str(), &buffer) == 0;
diff --git a/xplat/Sonar/SonarWebSocketImpl.h b/xplat/Sonar/SonarWebSocketImpl.h
index 7d91fcd18db..ca1e3710a02 100644
--- a/xplat/Sonar/SonarWebSocketImpl.h
+++ b/xplat/Sonar/SonarWebSocketImpl.h
@@ -62,6 +62,7 @@ class SonarWebSocketImpl : public SonarWebSocket {
   bool isCertificateExchangeNeeded();
   void requestSignedCertFromSonar();
   bool ensureSonarDirExists();
+  bool isRunningInOwnThread();
 };
 
 } // namespace sonar