QHttpNetworkConnectionChannel: reduce allocations

- don't use QMap::values, just iterate over QMap directly
- use const methods to avoid implicit detatch

While touching code, use isEmpty() to check container instead of size() with 0

Change-Id: I300b5f123f339dc92a4f932bd0b356f31ead3589
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

1 files changed, 22 insertions, 24 deletions

diff --git a/src/network/access/qhttpnetworkconnectionchannel.cpp b/src/network/access/qhttpnetworkconnectionchannel.cpp
index 4b278cadd6..032a280467 100644
--- a/src/network/access/qhttpnetworkconnectionchannel.cpp
+++ b/src/network/access/qhttpnetworkconnectionchannel.cpp
@@ -22,6 +22,7 @@
 #include "private/qnetconmonitor_p.h"
 
 #include <memory>
+#include <utility>
 
 QT_BEGIN_NAMESPACE
 
@@ -324,8 +325,8 @@ bool QHttpNetworkConnectionChannel::ensureConnection()
         QHttpNetworkReply *potentialReply = connection->d_func()->predictNextRequestsReply();
         if (potentialReply) {
             QMetaObject::invokeMethod(potentialReply, "socketStartedConnecting", Qt::QueuedConnection);
-        } else if (h2RequestsToSend.size() > 0) {
-            QMetaObject::invokeMethod(h2RequestsToSend.values().at(0).second, "socketStartedConnecting", Qt::QueuedConnection);
+        } else if (!h2RequestsToSend.isEmpty()) {
+            QMetaObject::invokeMethod(std::as_const(h2RequestsToSend).first().second, "socketStartedConnecting", Qt::QueuedConnection);
         }
 
 #ifndef QT_NO_NETWORKPROXY
@@ -343,8 +344,8 @@ bool QHttpNetworkConnectionChannel::ensureConnection()
                 if (connection->connectionType()
                             == QHttpNetworkConnection::ConnectionTypeHTTP2Direct
                     || (connection->connectionType() == QHttpNetworkConnection::ConnectionTypeHTTP2
-                        && h2RequestsToSend.size() > 0)) {
-                    value = h2RequestsToSend.first().first.headerField("user-agent");
+                        && !h2RequestsToSend.isEmpty())) {
+                    value = std::as_const(h2RequestsToSend).first().first.headerField("user-agent");
                 } else {
                     value = connection->d_func()->predictNextRequest().headerField("user-agent");
                 }
@@ -1093,16 +1094,15 @@ void QHttpNetworkConnectionChannel::_q_error(QAbstractSocket::SocketError socket
 
     if (connection->connectionType() == QHttpNetworkConnection::ConnectionTypeHTTP2
         || connection->connectionType() == QHttpNetworkConnection::ConnectionTypeHTTP2Direct) {
-        QList<HttpMessagePair> h2Pairs = h2RequestsToSend.values();
-        for (int a = 0; a < h2Pairs.size(); ++a) {
+        const auto h2RequestsToSendCopy = std::exchange(h2RequestsToSend, {});
+        for (const auto &httpMessagePair : h2RequestsToSendCopy) {
             // emit error for all replies
-            QHttpNetworkReply *currentReply = h2Pairs.at(a).second;
+            QHttpNetworkReply *currentReply = httpMessagePair.second;
             currentReply->d_func()->errorString = errorString;
             currentReply->d_func()->httpErrorCode = errorCode;
             Q_ASSERT(currentReply);
             emit currentReply->finishedWithError(errorCode, errorString);
         }
-        h2RequestsToSend.clear();
     }
 
     // send the next request
@@ -1151,9 +1151,9 @@ void QHttpNetworkConnectionChannel::emitFinishedWithError(QNetworkReply::Network
 {
     if (reply)
         emit reply->finishedWithError(error, QHttpNetworkConnectionChannel::tr(message));
-    QList<HttpMessagePair> h2Pairs = h2RequestsToSend.values();
-    for (int a = 0; a < h2Pairs.size(); ++a) {
-        QHttpNetworkReply *currentReply = h2Pairs.at(a).second;
+    const auto h2RequestsToSendCopy = h2RequestsToSend;
+    for (const auto &httpMessagePair : h2RequestsToSendCopy) {
+        QHttpNetworkReply *currentReply = httpMessagePair.second;
         Q_ASSERT(currentReply);
         emit currentReply->finishedWithError(error, QHttpNetworkConnectionChannel::tr(message));
     }
@@ -1234,10 +1234,9 @@ void QHttpNetworkConnectionChannel::_q_encrypted()
 
     if (connection->connectionType() == QHttpNetworkConnection::ConnectionTypeHTTP2 ||
         connection->connectionType() == QHttpNetworkConnection::ConnectionTypeHTTP2Direct) {
-        if (h2RequestsToSend.size() > 0) {
+        if (!h2RequestsToSend.isEmpty()) {
             // Similar to HTTP/1.1 counterpart below:
-            const auto &h2Pairs = h2RequestsToSend.values(); // (request, reply)
-            const auto &pair = h2Pairs.first();
+            const auto &pair = std::as_const(h2RequestsToSend).first();
             emit pair.second->encrypted();
             // In case our peer has sent us its settings (window size, max concurrent streams etc.)
             // let's give _q_receiveReply a chance to read them first ('invokeMethod', QueuedConnection).
@@ -1258,10 +1257,9 @@ void QHttpNetworkConnectionChannel::_q_encrypted()
 
 void QHttpNetworkConnectionChannel::requeueHttp2Requests()
 {
-    QList<HttpMessagePair> h2Pairs = h2RequestsToSend.values();
-    for (int a = 0; a < h2Pairs.size(); ++a)
-        connection->d_func()->requeueRequest(h2Pairs.at(a));
-    h2RequestsToSend.clear();
+    const auto h2RequestsToSendCopy = std::exchange(h2RequestsToSend, {});
+    for (const auto &httpMessagePair : h2RequestsToSendCopy)
+        connection->d_func()->requeueRequest(httpMessagePair);
 }
 
 void QHttpNetworkConnectionChannel::_q_sslErrors(const QList<QSslError> &errors)
@@ -1280,10 +1278,10 @@ void QHttpNetworkConnectionChannel::_q_sslErrors(const QList<QSslError> &errors)
     }
 #ifndef QT_NO_SSL
     else { // HTTP/2
-        QList<HttpMessagePair> h2Pairs = h2RequestsToSend.values();
-        for (int a = 0; a < h2Pairs.size(); ++a) {
+        const auto h2RequestsToSendCopy = h2RequestsToSend;
+        for (const auto &httpMessagePair : h2RequestsToSendCopy) {
             // emit SSL errors for all replies
-            QHttpNetworkReply *currentReply = h2Pairs.at(a).second;
+            QHttpNetworkReply *currentReply = httpMessagePair.second;
             Q_ASSERT(currentReply);
             emit currentReply->sslErrors(errors);
         }
@@ -1303,10 +1301,10 @@ void QHttpNetworkConnectionChannel::_q_preSharedKeyAuthenticationRequired(QSslPr
         if (reply)
             emit reply->preSharedKeyAuthenticationRequired(authenticator);
     } else {
-        QList<HttpMessagePair> h2Pairs = h2RequestsToSend.values();
-        for (int a = 0; a < h2Pairs.size(); ++a) {
+        const auto h2RequestsToSendCopy = h2RequestsToSend;
+        for (const auto &httpMessagePair : h2RequestsToSendCopy) {
             // emit SSL errors for all replies
-            QHttpNetworkReply *currentReply = h2Pairs.at(a).second;
+            QHttpNetworkReply *currentReply = httpMessagePair.second;
             Q_ASSERT(currentReply);
             emit currentReply->preSharedKeyAuthenticationRequired(authenticator);
         }