jruby · Mar 26, 2018 · Mar 26, 2018 · Mar 26, 2018
Showing with 64 additions and 6 deletions.

+16 −5 core/src/main/java/org/jruby/RubyException.java

+39 −0 spec/ruby/core/exception/backtrace_locations_spec.rb

+9 −1 spec/ruby/core/exception/fixtures/common.rb
diff --git a/core/src/main/java/org/jruby/RubyException.java b/core/src/main/java/org/jruby/RubyException.java
@@ -107,10 +107,19 @@ private void setBacktrace(IRubyObject obj) {
 
     @JRubyMethod(omit = true)
     public IRubyObject backtrace_locations(ThreadContext context) {
+        BacktraceData backtraceData = this.backtraceData;
+
+        if (backtraceData == null) return context.nil;
+
+        RubyArray backtraceLocations = this.backtraceLocations;
+
+        if (backtraceLocations != null) return backtraceLocations;
+
         Ruby runtime = context.runtime;
+
         RubyStackTraceElement[] elements = backtraceData.getBacktrace(runtime);
 
-        return RubyThread.Location.newLocationArray(runtime, elements);
+        return backtraceLocations = this.backtraceLocations = RubyThread.Location.newLocationArray(runtime, elements);
     }
 
     @JRubyMethod(name = "exception", optional = 1, rest = true, meta = true)
@@ -216,6 +225,7 @@ public Object getCause() {
 
     public void setBacktraceData(BacktraceData backtraceData) {
         this.backtraceData = backtraceData;
+        this.backtraceLocations = null; // clear any generated locations
     }
 
     public BacktraceData getBacktraceData() {
@@ -232,7 +242,7 @@ public RubyStackTraceElement[] getBacktraceElements() {
     public void prepareBacktrace(ThreadContext context, boolean nativeException) {
         // if it's null, build a backtrace
         if (backtraceData == null) {
-            backtraceData = context.runtime.getInstanceConfig().getTraceType().getBacktrace(context, nativeException);
+            setBacktraceData(context.runtime.getInstanceConfig().getTraceType().getBacktrace(context, nativeException));
         }
     }
 
@@ -246,12 +256,12 @@ public void prepareBacktrace(ThreadContext context, boolean nativeException) {
     public void prepareIntegratedBacktrace(ThreadContext context, StackTraceElement[] javaTrace) {
         // if it's null, build a backtrace
         if (backtraceData == null) {
-            backtraceData = context.runtime.getInstanceConfig().getTraceType().getIntegratedBacktrace(context, javaTrace);
+            setBacktraceData(context.runtime.getInstanceConfig().getTraceType().getIntegratedBacktrace(context, javaTrace));
         }
     }
 
     public void forceBacktrace(IRubyObject backtrace) {
-        backtraceData = (backtrace != null && backtrace.isNil()) ? null : BacktraceData.EMPTY;
+        setBacktraceData((backtrace != null && backtrace.isNil()) ? null : BacktraceData.EMPTY);
         setBacktrace(backtrace);
     }
 
@@ -275,7 +285,7 @@ public void initBacktrace() {
     @SuppressWarnings("deprecated")
     public void copySpecialInstanceVariables(IRubyObject clone) {
         RubyException exception = (RubyException)clone;
-        exception.backtraceData = backtraceData;
+        exception.setBacktraceData(backtraceData);
         exception.backtrace = backtrace;
         exception.message = message;
     }
@@ -413,6 +423,7 @@ public String getMessageAsJavaString() {
 
     private BacktraceData backtraceData;
     private IRubyObject backtrace;
+    private RubyArray backtraceLocations;
     IRubyObject message;
     IRubyObject cause;
 

diff --git a/spec/ruby/core/exception/backtrace_locations_spec.rb b/spec/ruby/core/exception/backtrace_locations_spec.rb
@@ -0,0 +1,39 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+require File.expand_path('../fixtures/common', __FILE__)
+
+describe "Exception#backtrace_locations" do
+  before :each do
+    @backtrace = ExceptionSpecs::Backtrace.backtrace_locations
+  end
+
+  it "returns nil if no backtrace was set" do
+    Exception.new.backtrace_locations.should be_nil
+  end
+
+  it "returns an Array" do
+    @backtrace.should be_an_instance_of(Array)
+  end
+
+  it "sets each element to a String" do
+    @backtrace.each {|l| l.should be_an_instance_of(Thread::Backtrace::Location)}
+  end
+
+  it "produces a backtrace for an exception captured using $!" do
+    exception = begin
+      raise
+    rescue RuntimeError
+      $!
+    end
+
+    exception.backtrace_locations.first.path.should =~ /backtrace_locations_spec/
+  end
+
+  it "returns an Array that can be updated" do
+    begin
+      raise
+    rescue RuntimeError => e
+      e.backtrace_locations.unshift "backtrace first"
+      e.backtrace_locations[0].should == "backtrace first"
+    end
+  end
+end
diff --git a/spec/ruby/core/exception/fixtures/common.rb b/spec/ruby/core/exception/fixtures/common.rb
@@ -4,11 +4,19 @@ class Exceptional < Exception; end
   class Backtrace
     def self.backtrace
       begin
-        raise # Do not move this line or update backtrace_spec.rb
+        raise # If you move this line, update backtrace_spec.rb
       rescue RuntimeError => e
         e.backtrace
       end
     end
+
+    def self.backtrace_locations
+      begin
+        raise
+      rescue RuntimeError => e
+        e.backtrace_locations
+      end
+    end
   end
 
   class UnExceptional < Exception