QAndroidActivityResultReceiver: avoid double(triple)-lookup

The code used the if (!contains()) { insert() } anti-pattern,
necessitated by Qt's deviation from the STL of allowing insert() to
overwrite an existing entry, causing two lookups of the same key.

Fix by recording the size prior to the execution of the indexing
operator and taking a size increase as the cue to populate the (new)
entry. This way, we look up the key only once.

Also fix two instances of double lookup caused by the if (contains())
{ value() } anti-pattern.

Change-Id: I961fe45ec571aa94aff5dd578f2276e7b74d800d
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

1 files changed, 9 insertions, 6 deletions

diff --git a/src/corelib/platform/android/qandroidextras.cpp b/src/corelib/platform/android/qandroidextras.cpp
index 7de28f5a12..1da8bcf265 100644
--- a/src/corelib/platform/android/qandroidextras.cpp
+++ b/src/corelib/platform/android/qandroidextras.cpp
@@ -501,19 +501,22 @@ public:
 
     int globalRequestCode(int localRequestCode) const
     {
-        if (!localToGlobalRequestCode.contains(localRequestCode)) {
+        const auto oldSize = localToGlobalRequestCode.size();
+        auto &e = localToGlobalRequestCode[localRequestCode];
+        if (localToGlobalRequestCode.size() != oldSize) {
+            // new entry, populate:
             int globalRequestCode = uniqueActivityRequestCode();
-            localToGlobalRequestCode[localRequestCode] = globalRequestCode;
+            e = globalRequestCode;
             globalToLocalRequestCode[globalRequestCode] = localRequestCode;
         }
-        return localToGlobalRequestCode.value(localRequestCode);
+        return e;
     }
 
     bool handleActivityResult(jint requestCode, jint resultCode, jobject data)
     {
-        if (globalToLocalRequestCode.contains(requestCode)) {
-            q->handleActivityResult(globalToLocalRequestCode.value(requestCode),
-                                    resultCode, QJniObject(data));
+        const auto it = std::as_const(globalToLocalRequestCode).find(requestCode);
+        if (it != globalToLocalRequestCode.cend()) {
+            q->handleActivityResult(*it, resultCode, QJniObject(data));
             return true;
         }