wsd: avoid repeated regex construction

std::regex is expensive to construct
and is best cached.

Change-Id: I342003d1951a625d8f94597db2bff9d0d81f9696
Signed-off-by: Ashod Nakashian <ashod.nakashian@collabora.co.uk>

Author: Ashod

wsd/AdminModel.cpp

@@ -987,12 +987,14 @@ int AdminModel::getPidsFromProcName(const std::regex& procNameRegEx, std::vector
 
 int AdminModel::getAssignedKitPids(std::vector<int> *pids)
 {
-    return getPidsFromProcName(std::regex("kitbroker_.*"), pids);
+    static const std::regex re("kitbroker_.*");
+    return getPidsFromProcName(re, pids);
 }
 
 int AdminModel::getUnassignedKitPids(std::vector<int> *pids)
 {
-    return getPidsFromProcName(std::regex("kit_spare_.*"), pids);
+    static const std::regex re("kit_spare_.*");
+    return getPidsFromProcName(re, pids);
 }
 
 void AdminModel::getKitPidsFromSystem(std::vector<int> *pids)
@@ -1200,7 +1202,10 @@ void AdminModel::getMetrics(std::ostream& oss) const
 {
     ASSERT_CORRECT_THREAD_OWNER(_owner);
 
-    oss << "coolwsd_count " << getPidsFromProcName(std::regex("coolwsd"), nullptr) << '\n';
+    static const std::regex coolwsdRe("coolwsd");
+    static const std::regex forkitRe("forkit");
+
+    oss << "coolwsd_count " << getPidsFromProcName(coolwsdRe, nullptr) << '\n';
     oss << "coolwsd_thread_count " << ProcUtil::getStatFromPid(ProcUtil::getProcessId(), 19)
         << '\n';
     oss << "coolwsd_cpu_time_seconds "
@@ -1210,7 +1215,7 @@ void AdminModel::getMetrics(std::ostream& oss) const
     oss << "coolwsd_tcp_connections_used " << StreamSocket::getExternalConnectionCount() << '\n';
     oss << '\n';
 
-    oss << "forkit_count " << getPidsFromProcName(std::regex("forkit"), nullptr) << '\n';
+    oss << "forkit_count " << getPidsFromProcName(forkitRe, nullptr) << '\n';
     oss << "forkit_thread_count " << ProcUtil::getStatFromPid(_forKitPid, 19) << '\n';
     oss << "forkit_cpu_time_seconds " << ProcUtil::getCpuUsage(_forKitPid) / sysconf (_SC_CLK_TCK) << '\n';
     oss << "forkit_memory_used_bytes " << ProcUtil::getMemoryUsageRSS(_forKitPid) * 1024 << '\n';

wsd/HostUtil.cpp

@@ -91,7 +91,7 @@ std::string HostUtil::parseAlias(const std::string& aliasPattern)
     // check if it is plain uri, then convert to a strict regex for this uri if needed
     // Must be a full match.
     // Group 2 captures the hostname.
-    std::regex re(
+    static const std::regex re(
         "^(https?://)?(([a-z0-9\\-]+)(\\.[a-z0-9\\-]+)*)(:[0-9]{1,5})?(/[a-z0-9\\-&?_]*)*$",
         std::regex_constants::icase);