From 32e2eaa965d935252472258d97575bbcd4d86481 Mon Sep 17 00:00:00 2001
From: Gian-Carlo Pascutto <gpascutto@mozilla.com>
Date: Wed, 15 Aug 2012 09:09:25 +0200
Subject: [PATCH] Bug 673470 - Make the PrefixSet/LookupCache construction
 infallible again. r=dcamp f=jlebar

---
 .../telemetry/TelemetryHistograms.h           |  2 +-
 .../components/url-classifier/LookupCache.cpp | 14 +++-------
 .../nsUrlClassifierPrefixSet.cpp              | 26 ++++++-------------
 3 files changed, 13 insertions(+), 29 deletions(-)

diff --git a/toolkit/components/telemetry/TelemetryHistograms.h b/toolkit/components/telemetry/TelemetryHistograms.h
index 774ad9f7ff9..cdc46b45ceb 100644
--- a/toolkit/components/telemetry/TelemetryHistograms.h
+++ b/toolkit/components/telemetry/TelemetryHistograms.h
@@ -355,7 +355,7 @@ HISTOGRAM(URLCLASSIFIER_PS_FALLOCATE_TIME, 1, 1000, 10, EXPONENTIAL, "Time spent
 HISTOGRAM(URLCLASSIFIER_PS_CONSTRUCT_TIME, 1, 5000, 15, EXPONENTIAL, "Time spent constructing PrefixSet from DB (ms)")
 HISTOGRAM(URLCLASSIFIER_LC_PREFIXES, 1, 1500000, 15, LINEAR, "Size of the prefix cache in entries")
 HISTOGRAM(URLCLASSIFIER_LC_COMPLETIONS, 1, 200, 10, EXPONENTIAL, "Size of the completion cache in entries")
-HISTOGRAM_BOOLEAN(URLCLASSIFIER_PS_OOM, "Did UrlClassifier run out of memory during PrefixSet construction?")
+HISTOGRAM_BOOLEAN(URLCLASSIFIER_PS_FAILURE, "Did UrlClassifier fail to construct the PrefixSet?")
 #endif
 
 /**
diff --git a/toolkit/components/url-classifier/LookupCache.cpp b/toolkit/components/url-classifier/LookupCache.cpp
index 7019b19d922..2c3370e7428 100644
--- a/toolkit/components/url-classifier/LookupCache.cpp
+++ b/toolkit/components/url-classifier/LookupCache.cpp
@@ -713,12 +713,8 @@ LookupCache::ConstructPrefixSet(AddPrefixArray& aAddPrefixes)
 {
   Telemetry::AutoTimer<Telemetry::URLCLASSIFIER_PS_CONSTRUCT_TIME> timer;
 
-  FallibleTArray<PRUint32> array;
-  nsresult rv;
-  if (!array.SetCapacity(aAddPrefixes.Length())) {
-    rv = NS_ERROR_OUT_OF_MEMORY;
-    goto error_bailout;
-  }
+  nsTArray<PRUint32> array;
+  array.SetCapacity(aAddPrefixes.Length());
 
   for (uint32 i = 0; i < aAddPrefixes.Length(); i++) {
     array.AppendElement(aAddPrefixes[i].PrefixHash().ToUint32());
@@ -735,7 +731,7 @@ LookupCache::ConstructPrefixSet(AddPrefixArray& aAddPrefixes)
 #endif
 
   // construct new one, replace old entries
-  rv = mPrefixSet->SetPrefixes(array.Elements(), array.Length());
+  nsresult rv = mPrefixSet->SetPrefixes(array.Elements(), array.Length());
   if (NS_FAILED(rv)) {
     goto error_bailout;
   }
@@ -756,9 +752,7 @@ LookupCache::ConstructPrefixSet(AddPrefixArray& aAddPrefixes)
   sentinel.Clear();
   sentinel.AppendElement(0);
   mPrefixSet->SetPrefixes(sentinel.Elements(), sentinel.Length());
-  if (rv == NS_ERROR_OUT_OF_MEMORY) {
-    Telemetry::Accumulate(Telemetry::URLCLASSIFIER_PS_OOM, 1);
-  }
+  Telemetry::Accumulate(Telemetry::URLCLASSIFIER_PS_FAILURE, 1);
   return rv;
 }
 
diff --git a/toolkit/components/url-classifier/nsUrlClassifierPrefixSet.cpp b/toolkit/components/url-classifier/nsUrlClassifierPrefixSet.cpp
index 69f5596be22..5025cbae6d6 100644
--- a/toolkit/components/url-classifier/nsUrlClassifierPrefixSet.cpp
+++ b/toolkit/components/url-classifier/nsUrlClassifierPrefixSet.cpp
@@ -165,34 +165,24 @@ nsUrlClassifierPrefixSet::MakePrefixSet(const PRUint32* aPrefixes, PRUint32 aLen
   }
 #endif
 
-  FallibleTArray<PRUint32> newIndexPrefixes;
-  FallibleTArray<PRUint32> newIndexStarts;
-  FallibleTArray<PRUint16> newDeltas;
+  nsTArray<PRUint32> newIndexPrefixes;
+  nsTArray<PRUint32> newIndexStarts;
+  nsTArray<PRUint16> newDeltas;
 
-  if (!newIndexPrefixes.AppendElement(aPrefixes[0])) {
-    return NS_ERROR_OUT_OF_MEMORY;
-  }
-  if (!newIndexStarts.AppendElement(newDeltas.Length())) {
-    return NS_ERROR_OUT_OF_MEMORY;
-  }
+  newIndexPrefixes.AppendElement(aPrefixes[0]);
+  newIndexStarts.AppendElement(newDeltas.Length());
 
   PRUint32 numOfDeltas = 0;
   PRUint32 currentItem = aPrefixes[0];
   for (PRUint32 i = 1; i < aLength; i++) {
     if ((numOfDeltas >= DELTAS_LIMIT) ||
           (aPrefixes[i] - currentItem >= MAX_INDEX_DIFF)) {
-      if (!newIndexStarts.AppendElement(newDeltas.Length())) {
-        return NS_ERROR_OUT_OF_MEMORY;
-      }
-      if (!newIndexPrefixes.AppendElement(aPrefixes[i])) {
-        return NS_ERROR_OUT_OF_MEMORY;
-      }
+      newIndexStarts.AppendElement(newDeltas.Length());
+      newIndexPrefixes.AppendElement(aPrefixes[i]);
       numOfDeltas = 0;
     } else {
       PRUint16 delta = aPrefixes[i] - currentItem;
-      if (!newDeltas.AppendElement(delta)) {
-        return NS_ERROR_OUT_OF_MEMORY;
-      }
+      newDeltas.AppendElement(delta);
       numOfDeltas++;
     }
     currentItem = aPrefixes[i];