From: Szymon Jastrzebski <s.jastrzebsk@partner.samsung.com>
Date: Tue, 20 Feb 2018 14:09:48 +0000 (+0100)
Subject: [Systeminfo] Prevention for unnecessary double mutex-locking
X-Git-Tag: submit/tizen/20180228.082430~5^2
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=a43e13cc4790658046f38d0eaa1a808cc47d7a1f;p=platform%2Fcore%2Fapi%2Fwebapi-plugins.git

[Systeminfo] Prevention for unnecessary double mutex-locking

The mutex locking may hang the application if all getters fail.

[Verification] Systeminfo TCT 100% pass rate + manually tested in console.

Change-Id: I270c6f5a5cb40f3975104476aa4e7de3179e0e64
Signed-off-by: Szymon Jastrzebski <s.jastrzebsk@partner.samsung.com>
---

diff --git a/src/systeminfo/systeminfo_sim_details_manager.cc b/src/systeminfo/systeminfo_sim_details_manager.cc
index 3fb1c228..8b85d5b2 100644
--- a/src/systeminfo/systeminfo_sim_details_manager.cc
+++ b/src/systeminfo/systeminfo_sim_details_manager.cc
@@ -146,6 +146,8 @@ PlatformResult SimDetailsManager::GatherSimInformation(TapiHandle* handle, picoj
     if (ret.IsError()) {
       return ret;
     }
+    // The variable used to determine if double mutex-locking is needed.
+    auto to_process_cached = to_process_;
     {
       // All props should be fetched synchronously, but sync function does not work
       std::lock_guard<std::mutex> lock_to_process(sim_to_process_mutex_);
@@ -178,8 +180,16 @@ PlatformResult SimDetailsManager::GatherSimInformation(TapiHandle* handle, picoj
         LoggerE("Failed getting iccid: %d", result);
       }
     }
-    // prevent returning not filled result
-    std::lock_guard<std::mutex> lock_sim(sim_info_mutex_);
+    // Here, the double mutex-locking may hang the application (thread) forever.
+    // This happens when none of above (4) getters succeeds (the to_process_ variable is not
+    // incremented).
+    // Usually, we would return and report an error, but the getPropertyValue and
+    // getPropertyValueArray methods do not invoke errorCallback with proper error type, thus silent
+    // error will be reported.
+    if (to_process_cached != to_process_) {
+      // Try to lock and wait for unlocking the sim_info_mutex_ by all registered callbacks.
+      std::lock_guard<std::mutex> lock_sim(sim_info_mutex_);
+    }
     // result will come from callbacks
     return PlatformResult(ErrorCode::NO_ERROR);
   }