add idxniceprio parameter to choose indexing process priority

src/index/recollindex.cpp

@@ -233,6 +233,7 @@ void rclIxIonice(const RclConfig *config)
     string clss, classdata;
     if (!config->getConfParam("monioniceclass", clss) || clss.empty())
         clss = "3";
+    // Classdata may be empty (must be for idle class)
     config->getConfParam("monioniceclassdata", classdata);
     rclionice(clss, classdata);
 #endif
@@ -241,7 +242,13 @@ void rclIxIonice(const RclConfig *config)
 static void setMyPriority(const RclConfig *config)
 {
 #ifndef _WIN32
-    if (setpriority(PRIO_PROCESS, 0, 20) != 0) {
+    int prio{19};
+    std::string sprio;
+    config->getConfParam("idxniceprio", sprio);
+    if (!sprio.empty()) {
+        prio = atoi(sprio.c_str());
+    }
+    if (setpriority(PRIO_PROCESS, 0, prio) != 0) {
         LOGINFO("recollindex: can't setpriority(), errno " << errno << "\n");
     }
     // Try to ionice. This does not work on all platforms

src/sampleconf/recoll.conf

@@ -817,18 +817,38 @@ checkneedretryindexscript = rclcheckneedretry.sh
 # Example: mondelaypatterns = *.log:20 "*with spaces.*:30"</descr></var>
 #mondelaypatterns = *.log:20  "*with spaces.*:30"
 
+# <var name="idxniceprio" type="int">
+#
+# <brief>"nice" process priority for the indexing processes. Default: 19
+# (lowest)</brief>
+#
+# <descr>Appeared with 1.26.5. Prior versions were fixed at 19.</descr>
+#
+# </var> 
+#idxniceprio = 19
+
+
 # <var name="monioniceclass" type="int">
 #
-# <brief>ionice class for the real time indexing process</brief>
-# <descr>On platforms where this is supported. The default value is
-# 3.</descr></var> 
+# <brief>ionice class for the indexing process.</brief>
+#
+# <descr>Despite the misleading name, and on platforms where this is
+# supported, this affects all indexing processes,
+# not only the real time/monitoring ones. The default value is 3 (use
+# lowest "Idle" priority).</descr>
+#
+# </var> 
 #monioniceclass = 3
 
 # <var name="monioniceclassdata" type="string">
 #
-# <brief>ionice class parameter for the real time indexing process.</brief>
-# <descr>On platforms where this is supported. The default is
-# empty.</descr></var>
+# <brief>ionice class level parameter if the class supports it.</brief>
+#
+# <descr>The default is empty, as the default "Idle" class has no
+# levels.</descr> 
+#
+# </var>
+#
 #monioniceclassdata = 
 
 

src/utils/rclionice.cpp

@@ -51,9 +51,8 @@ bool rclionice(const string& clss, const string& cdata)
     int status = cmd.doexec(ionicexe, args);
 
     if (status) {
-	LOGERR("rclionice: failed, status 0x"  << (status) << "\n" );
+        LOGERR("rclionice: failed, status 0x" << status << "\n");
         return false;
     }
     return true;
 }
-