callstack: Fix callstack concurrency exceptions

The CallStackDepth class used by data provider should use the object ID
of the callstack in its hash code, as 2 objects will be equivalent if
they refer to the same callstack, no matter its content.

Also, avoid concurrency exceptions while building by synchronizing
access to attribute updates

Change-Id: Idb806ab30e9b6d063ecbdce2a94cb045e8404200
Signed-off-by: Geneviève Bastien <gbastien+lttng@versatic.net>
Reviewed-on: https://git.eclipse.org/r/121975
Tested-by: CI Bot
Reviewed-by: Matthew Khouzam <matthew.khouzam@ericsson.com>
Tested-by: Matthew Khouzam <matthew.khouzam@ericsson.com>

2 files changed, 13 insertions, 5 deletions

diff --git a/callstack/org.eclipse.tracecompass.incubator.callstack.core/src/org/eclipse/tracecompass/incubator/callstack/core/instrumented/CallStackDepth.java b/callstack/org.eclipse.tracecompass.incubator.callstack.core/src/org/eclipse/tracecompass/incubator/callstack/core/instrumented/CallStackDepth.java
index fbcf8da16..2a408e0cd 100644
--- a/callstack/org.eclipse.tracecompass.incubator.callstack.core/src/org/eclipse/tracecompass/incubator/callstack/core/instrumented/CallStackDepth.java
+++ b/callstack/org.eclipse.tracecompass.incubator.callstack.core/src/org/eclipse/tracecompass/incubator/callstack/core/instrumented/CallStackDepth.java
@@ -59,7 +59,10 @@ public class CallStackDepth {
 
     @Override
     public int hashCode() {
-        return Objects.hashCode(fCallstack, fDepth);
+        // Compare with the actual callstack object, as the callstack's own hash may
+        // change as the callstack is built. Here, we are looking for the same object,
+        // no matter its content
+        return Objects.hashCode(System.identityHashCode(fCallstack), fDepth);
     }
 
     @Override
@@ -68,7 +71,10 @@ public class CallStackDepth {
             return false;
         }
         CallStackDepth csd = (CallStackDepth) obj;
-        return Objects.equal(fCallstack, csd.fCallstack) && (fDepth == csd.fDepth);
+        // Compare with the actual callstack object, as the callstack's own hash may
+        // change as the callstack is built. Here, we are looking for the same object,
+        // no matter its content
+        return Objects.equal(System.identityHashCode(fCallstack), System.identityHashCode(csd.fCallstack)) && (fDepth == csd.fDepth);
     }
 
     @Override
diff --git a/callstack/org.eclipse.tracecompass.incubator.callstack.core/src/org/eclipse/tracecompass/incubator/internal/callstack/core/instrumented/InstrumentedCallStackElement.java b/callstack/org.eclipse.tracecompass.incubator.callstack.core/src/org/eclipse/tracecompass/incubator/internal/callstack/core/instrumented/InstrumentedCallStackElement.java
index 85d9ee65f..6d82ef60d 100644
--- a/callstack/org.eclipse.tracecompass.incubator.callstack.core/src/org/eclipse/tracecompass/incubator/internal/callstack/core/instrumented/InstrumentedCallStackElement.java
+++ b/callstack/org.eclipse.tracecompass.incubator.callstack.core/src/org/eclipse/tracecompass/incubator/internal/callstack/core/instrumented/InstrumentedCallStackElement.java
@@ -236,9 +236,11 @@ public class InstrumentedCallStackElement extends CallStackElement {
             callstack =  new CallStack(getStateSystem(), subAttributes, this, hostProvider, threadIdProvider);
             fCallstack = callstack;
         } else {
-            // Update the callstack if attributes were added
-            if (callstack.getMaxDepth() < subAttributes.size() ) {
-                callstack.updateAttributes(subAttributes);
+            synchronized (fCallstack) {
+                // Update the callstack if attributes were added
+                if (callstack.getMaxDepth() < subAttributes.size()) {
+                    callstack.updateAttributes(subAttributes);
+                }
             }
         }
         return Objects.requireNonNull(callstack);