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<dl class="meta">
<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/170677">170677</a></dd>
<dt>Author</dt> <dd>mark.lam@apple.com</dd>
<dt>Date</dt> <dd>2014-07-01 16:40:32 -0700 (Tue, 01 Jul 2014)</dd>
</dl>
<h3>Log Message</h3>
<pre>Debugger's breakpoint list should not be a Vector.
<https://webkit.org/b/134514>
Reviewed by Geoffrey Garen.
The debugger currently stores breakpoint data as entries in a Vector (see
BreakpointsInLine). It also keeps a fast map look up of breakpoint IDs to
the breakpoint data (see m_breakpointIDToBreakpoint). Because a Vector can
compact or reallocate its backing store, this can causes all sorts of havoc.
The m_breakpointIDToBreakpoint map assumes that the breakpoint data doesn't
move in memory.
The fix is to replace the BreakpointsInLine Vector with a BreakpointsList
doubly linked list.
* debugger/Breakpoint.h:
(JSC::Breakpoint::Breakpoint):
(JSC::BreakpointsList::~BreakpointsList):
* debugger/Debugger.cpp:
(JSC::Debugger::setBreakpoint):
(JSC::Debugger::removeBreakpoint):
(JSC::Debugger::hasBreakpoint):
* debugger/Debugger.h:</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceJavaScriptCoreChangeLog">trunk/Source/JavaScriptCore/ChangeLog</a></li>
<li><a href="#trunkSourceJavaScriptCoredebuggerBreakpointh">trunk/Source/JavaScriptCore/debugger/Breakpoint.h</a></li>
<li><a href="#trunkSourceJavaScriptCoredebuggerDebuggercpp">trunk/Source/JavaScriptCore/debugger/Debugger.cpp</a></li>
<li><a href="#trunkSourceJavaScriptCoredebuggerDebuggerh">trunk/Source/JavaScriptCore/debugger/Debugger.h</a></li>
</ul>
</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkSourceJavaScriptCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/ChangeLog (170676 => 170677)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/ChangeLog 2014-07-01 23:40:06 UTC (rev 170676)
+++ trunk/Source/JavaScriptCore/ChangeLog 2014-07-01 23:40:32 UTC (rev 170677)
</span><span class="lines">@@ -1,3 +1,29 @@
</span><ins>+2014-07-01 Mark Lam <mark.lam@apple.com>
+
+ Debugger's breakpoint list should not be a Vector.
+ <https://webkit.org/b/134514>
+
+ Reviewed by Geoffrey Garen.
+
+ The debugger currently stores breakpoint data as entries in a Vector (see
+ BreakpointsInLine). It also keeps a fast map look up of breakpoint IDs to
+ the breakpoint data (see m_breakpointIDToBreakpoint). Because a Vector can
+ compact or reallocate its backing store, this can causes all sorts of havoc.
+ The m_breakpointIDToBreakpoint map assumes that the breakpoint data doesn't
+ move in memory.
+
+ The fix is to replace the BreakpointsInLine Vector with a BreakpointsList
+ doubly linked list.
+
+ * debugger/Breakpoint.h:
+ (JSC::Breakpoint::Breakpoint):
+ (JSC::BreakpointsList::~BreakpointsList):
+ * debugger/Debugger.cpp:
+ (JSC::Debugger::setBreakpoint):
+ (JSC::Debugger::removeBreakpoint):
+ (JSC::Debugger::hasBreakpoint):
+ * debugger/Debugger.h:
+
</ins><span class="cx"> 2014-06-30 Michael Saboff <msaboff@apple.com>
</span><span class="cx">
</span><span class="cx"> Add option to run-jsc-stress-testes to filter out tests that use large heaps
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoredebuggerBreakpointh"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/debugger/Breakpoint.h (170676 => 170677)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/debugger/Breakpoint.h 2014-07-01 23:40:06 UTC (rev 170676)
+++ trunk/Source/JavaScriptCore/debugger/Breakpoint.h 2014-07-01 23:40:32 UTC (rev 170677)
</span><span class="lines">@@ -27,11 +27,13 @@
</span><span class="cx"> #define Breakpoint_h
</span><span class="cx">
</span><span class="cx"> #include "DebuggerPrimitives.h"
</span><ins>+#include <wtf/DoublyLinkedList.h>
+#include <wtf/RefCounted.h>
</ins><span class="cx"> #include <wtf/text/WTFString.h>
</span><span class="cx">
</span><span class="cx"> namespace JSC {
</span><span class="cx">
</span><del>-struct Breakpoint {
</del><ins>+struct Breakpoint : public DoublyLinkedListNode<Breakpoint> {
</ins><span class="cx"> Breakpoint()
</span><span class="cx"> : id(noBreakpointID)
</span><span class="cx"> , sourceID(noSourceID)
</span><span class="lines">@@ -51,6 +53,16 @@
</span><span class="cx"> {
</span><span class="cx"> }
</span><span class="cx">
</span><ins>+ Breakpoint(const Breakpoint& other)
+ : id(other.id)
+ , sourceID(other.sourceID)
+ , line(other.line)
+ , column(other.column)
+ , condition(other.condition)
+ , autoContinue(other.autoContinue)
+ {
+ }
+
</ins><span class="cx"> BreakpointID id;
</span><span class="cx"> SourceID sourceID;
</span><span class="cx"> unsigned line;
</span><span class="lines">@@ -59,8 +71,26 @@
</span><span class="cx"> bool autoContinue;
</span><span class="cx">
</span><span class="cx"> static const unsigned unspecifiedColumn = UINT_MAX;
</span><ins>+
+private:
+ Breakpoint* m_prev;
+ Breakpoint* m_next;
+
+ friend class WTF::DoublyLinkedListNode<Breakpoint>;
</ins><span class="cx"> };
</span><span class="cx">
</span><ins>+class BreakpointsList : public DoublyLinkedList<Breakpoint>,
+ public RefCounted<BreakpointsList> {
+public:
+ ~BreakpointsList()
+ {
+ Breakpoint* breakpoint;
+ while ((breakpoint = removeHead()))
+ delete breakpoint;
+ ASSERT(isEmpty());
+ }
+};
+
</ins><span class="cx"> } // namespace JSC
</span><span class="cx">
</span><span class="cx"> #endif // Breakpoint_h
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoredebuggerDebuggercpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/debugger/Debugger.cpp (170676 => 170677)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/debugger/Debugger.cpp 2014-07-01 23:40:06 UTC (rev 170676)
+++ trunk/Source/JavaScriptCore/debugger/Debugger.cpp 2014-07-01 23:40:32 UTC (rev 170677)
</span><span class="lines">@@ -357,18 +357,18 @@
</span><span class="cx"> it = m_sourceIDToBreakpoints.set(sourceID, LineToBreakpointsMap()).iterator;
</span><span class="cx"> LineToBreakpointsMap::iterator breaksIt = it->value.find(line);
</span><span class="cx"> if (breaksIt == it->value.end())
</span><del>- breaksIt = it->value.set(line, BreakpointsInLine()).iterator;
</del><ins>+ breaksIt = it->value.set(line, adoptRef(new BreakpointsList)).iterator;
</ins><span class="cx">
</span><del>- BreakpointsInLine& breakpoints = breaksIt->value;
- unsigned breakpointsCount = breakpoints.size();
- for (unsigned i = 0; i < breakpointsCount; i++)
- if (breakpoints[i].column == column) {
</del><ins>+ BreakpointsList& breakpoints = *breaksIt->value;
+ for (Breakpoint* current = breakpoints.head(); current; current = current->next()) {
+ if (current->column == column) {
</ins><span class="cx"> // The breakpoint already exists. We're not allowed to create a new
</span><span class="cx"> // breakpoint at this location. Rather than returning the breakpointID
</span><span class="cx"> // of the pre-existing breakpoint, we need to return noBreakpointID
</span><span class="cx"> // to indicate that we're not creating a new one.
</span><span class="cx"> return noBreakpointID;
</span><span class="cx"> }
</span><ins>+ }
</ins><span class="cx">
</span><span class="cx"> BreakpointID id = ++m_topBreakpointID;
</span><span class="cx"> RELEASE_ASSERT(id != noBreakpointID);
</span><span class="lines">@@ -377,8 +377,9 @@
</span><span class="cx"> actualLine = line;
</span><span class="cx"> actualColumn = column;
</span><span class="cx">
</span><del>- breakpoints.append(breakpoint);
- m_breakpointIDToBreakpoint.set(id, &breakpoints.last());
</del><ins>+ Breakpoint* newBreakpoint = new Breakpoint(breakpoint);
+ breakpoints.append(newBreakpoint);
+ m_breakpointIDToBreakpoint.set(id, newBreakpoint);
</ins><span class="cx">
</span><span class="cx"> toggleBreakpoint(breakpoint, BreakpointEnabled);
</span><span class="cx">
</span><span class="lines">@@ -391,31 +392,35 @@
</span><span class="cx">
</span><span class="cx"> BreakpointIDToBreakpointMap::iterator idIt = m_breakpointIDToBreakpoint.find(id);
</span><span class="cx"> ASSERT(idIt != m_breakpointIDToBreakpoint.end());
</span><del>- Breakpoint& breakpoint = *idIt->value;
</del><ins>+ Breakpoint* breakpoint = idIt->value;
</ins><span class="cx">
</span><del>- SourceID sourceID = breakpoint.sourceID;
</del><ins>+ SourceID sourceID = breakpoint->sourceID;
</ins><span class="cx"> ASSERT(sourceID);
</span><span class="cx"> SourceIDToBreakpointsMap::iterator it = m_sourceIDToBreakpoints.find(sourceID);
</span><span class="cx"> ASSERT(it != m_sourceIDToBreakpoints.end());
</span><del>- LineToBreakpointsMap::iterator breaksIt = it->value.find(breakpoint.line);
</del><ins>+ LineToBreakpointsMap::iterator breaksIt = it->value.find(breakpoint->line);
</ins><span class="cx"> ASSERT(breaksIt != it->value.end());
</span><span class="cx">
</span><del>- toggleBreakpoint(breakpoint, BreakpointDisabled);
</del><ins>+ toggleBreakpoint(*breakpoint, BreakpointDisabled);
</ins><span class="cx">
</span><del>- BreakpointsInLine& breakpoints = breaksIt->value;
- unsigned breakpointsCount = breakpoints.size();
- for (unsigned i = 0; i < breakpointsCount; i++) {
- if (breakpoints[i].id == breakpoint.id) {
- breakpoints.remove(i);
- m_breakpointIDToBreakpoint.remove(idIt);
</del><ins>+ BreakpointsList& breakpoints = *breaksIt->value;
+#if !ASSERT_DISABLED
+ bool found = false;
+ for (Breakpoint* current = breakpoints.head(); current && !found; current = current->next()) {
+ if (current->id == breakpoint->id)
+ found = true;
+ }
+ ASSERT(found);
+#endif
</ins><span class="cx">
</span><del>- if (breakpoints.isEmpty()) {
- it->value.remove(breaksIt);
- if (it->value.isEmpty())
- m_sourceIDToBreakpoints.remove(it);
- }
- break;
- }
</del><ins>+ m_breakpointIDToBreakpoint.remove(idIt);
+ breakpoints.remove(breakpoint);
+ delete breakpoint;
+
+ if (breakpoints.isEmpty()) {
+ it->value.remove(breaksIt);
+ if (it->value.isEmpty())
+ m_sourceIDToBreakpoints.remove(it);
</ins><span class="cx"> }
</span><span class="cx"> }
</span><span class="cx">
</span><span class="lines">@@ -436,12 +441,11 @@
</span><span class="cx"> return false;
</span><span class="cx">
</span><span class="cx"> bool hit = false;
</span><del>- const BreakpointsInLine& breakpoints = breaksIt->value;
- unsigned breakpointsCount = breakpoints.size();
- unsigned i;
- for (i = 0; i < breakpointsCount; i++) {
- unsigned breakLine = breakpoints[i].line;
- unsigned breakColumn = breakpoints[i].column;
</del><ins>+ const BreakpointsList& breakpoints = *breaksIt->value;
+ Breakpoint* breakpoint;
+ for (breakpoint = breakpoints.head(); breakpoint; breakpoint = breakpoint->next()) {
+ unsigned breakLine = breakpoint->line;
+ unsigned breakColumn = breakpoint->column;
</ins><span class="cx"> // Since frontend truncates the indent, the first statement in a line must match the breakpoint (line,0).
</span><span class="cx"> ASSERT(this == m_currentCallFrame->codeBlock()->globalObject()->debugger());
</span><span class="cx"> if ((line != m_lastExecutedLine && line == breakLine && !breakColumn)
</span><span class="lines">@@ -454,9 +458,9 @@
</span><span class="cx"> return false;
</span><span class="cx">
</span><span class="cx"> if (hitBreakpoint)
</span><del>- *hitBreakpoint = breakpoints[i];
</del><ins>+ *hitBreakpoint = *breakpoint;
</ins><span class="cx">
</span><del>- if (breakpoints[i].condition.isEmpty())
</del><ins>+ if (breakpoint->condition.isEmpty())
</ins><span class="cx"> return true;
</span><span class="cx">
</span><span class="cx"> // We cannot stop in the debugger while executing condition code,
</span><span class="lines">@@ -465,7 +469,7 @@
</span><span class="cx">
</span><span class="cx"> JSValue exception;
</span><span class="cx"> DebuggerCallFrame* debuggerCallFrame = currentDebuggerCallFrame();
</span><del>- JSValue result = debuggerCallFrame->evaluate(breakpoints[i].condition, exception);
</del><ins>+ JSValue result = debuggerCallFrame->evaluate(breakpoint->condition, exception);
</ins><span class="cx">
</span><span class="cx"> // We can lose the debugger while executing JavaScript.
</span><span class="cx"> if (!m_currentCallFrame)
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoredebuggerDebuggerh"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/debugger/Debugger.h (170676 => 170677)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/debugger/Debugger.h 2014-07-01 23:40:06 UTC (rev 170676)
+++ trunk/Source/JavaScriptCore/debugger/Debugger.h 2014-07-01 23:40:32 UTC (rev 170677)
</span><span class="lines">@@ -29,7 +29,6 @@
</span><span class="cx"> #include <wtf/HashMap.h>
</span><span class="cx"> #include <wtf/HashSet.h>
</span><span class="cx"> #include <wtf/RefPtr.h>
</span><del>-#include <wtf/Vector.h>
</del><span class="cx"> #include <wtf/text/TextPosition.h>
</span><span class="cx">
</span><span class="cx"> namespace JSC {
</span><span class="lines">@@ -128,8 +127,7 @@
</span><span class="cx"> private:
</span><span class="cx"> typedef HashMap<BreakpointID, Breakpoint*> BreakpointIDToBreakpointMap;
</span><span class="cx">
</span><del>- typedef Vector<Breakpoint> BreakpointsInLine;
- typedef HashMap<unsigned, BreakpointsInLine, WTF::IntHash<int>, WTF::UnsignedWithZeroKeyHashTraits<int>> LineToBreakpointsMap;
</del><ins>+ typedef HashMap<unsigned, RefPtr<BreakpointsList>, WTF::IntHash<int>, WTF::UnsignedWithZeroKeyHashTraits<int>> LineToBreakpointsMap;
</ins><span class="cx"> typedef HashMap<SourceID, LineToBreakpointsMap, WTF::IntHash<SourceID>, WTF::UnsignedWithZeroKeyHashTraits<SourceID>> SourceIDToBreakpointsMap;
</span><span class="cx">
</span><span class="cx"> class ClearCodeBlockDebuggerRequestsFunctor;
</span></span></pre>
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