#50 Process initialization is now parallel

Also adds some `info` level prints to make demos a bit more friendly to new users

closes #50

src/demos_scheduler.hpp

@@ -70,7 +70,7 @@ class DemosScheduler
 
     void start_scheduler()
     {
-        logger->debug("Starting scheduler");
+        logger->info("Starting scheduler");
         memory_tracker::enable();
         mf.start(std::chrono::steady_clock::now());
     }

src/partition_manager.hpp

@@ -10,11 +10,10 @@ class PartitionManager
 {
 private:
     Partitions partitions;
-    Partitions::iterator init_iter = partitions.begin();
-    Process *initialized_proc = nullptr;
     std::function<void()> completion_cb = [] {};
     // initialized in `run_process_init`
     std::function<void()> init_cb = nullptr;
+    int remaining_process_inits = 0;
 
 public:
     explicit PartitionManager(Partitions &&partitions)
@@ -54,12 +53,33 @@ class PartitionManager
         }
 
         // overwrite process exit callback set in constructor
-        // we need this to be able to detect that a process exited during initialization
-        //  and we should move on to the next one, otherwise a deadlock would occur
+        // we need this to be able to detect that a process exited during initialization,
+        //  otherwise a deadlock would occur, waiting for the completion of an exited process
         // this will be reset to the original callback after initialization is finished
         set_exit_cb(&PartitionManager::process_init_exit_cb);
 
-        init_next_process();
+        // count and start all processes that needs initialization in parallel
+        for (auto &part : partitions) {
+            for (auto &proc : part.processes) {
+                if (!proc.needs_initialization()) continue;
+                logger->trace("Initializing process '{}'", proc.get_pid());
+                remaining_process_inits++;
+                // resume the process; it should stop on its own after initialization is completed
+                // then, it will call proc_init_completion_cb as callback; if it exits instead
+                // (probably due to an error), `process_init_exit_cb` will be called
+                proc.resume();
+            }
+        }
+
+        if (remaining_process_inits == 0) {
+            logger->info("No processes need initialization");
+            // no process needs initialization, we're done
+            finish_process_init();
+        } else {
+            logger->info("Initializing {} {}",
+                         remaining_process_inits,
+                         remaining_process_inits == 1 ? "process" : "processes");
+        }
     }
 
     /** Spawns suspended processes from all partitions. */
@@ -113,45 +133,6 @@ class PartitionManager
         completion_cb();
     }
 
-    Process *find_next_uninitialized_process()
-    {
-        Process *proc;
-        for (; init_iter != partitions.end(); init_iter++) {
-            proc = init_iter->seek_pending_process();
-            if (proc) return proc;
-        }
-        return nullptr;
-    }
-
-    void init_next_process()
-    {
-        initialized_proc = find_next_uninitialized_process();
-        if (initialized_proc) {
-            init_process(initialized_proc);
-        } else {
-            finish_process_init();
-        }
-    }
-
-    /**
-     * Initializes a single process.
-     * Completion is handled by `process_init_completion_cb()`.
-     */
-    void init_process(Process *p)
-    {
-        if (!p->needs_initialization()) {
-            p->mark_completed();
-            init_next_process();
-            return;
-        }
-
-        logger->trace("Initializing process '{}'", p->get_pid());
-        // resume the process; it should stop on its own after initialization is completed
-        // then, it will call init_next_process as callback; if it exits instead (probably
-        //  due to an error), `process_init_exit_cb` will be called
-        p->resume();
-    }
-
     void finish_process_init()
     {
         // reset process exit cb to the original one
@@ -165,20 +146,20 @@ class PartitionManager
     }
 
     /** Called as a completion callback from process. */
-    void process_init_completion_cb(Process &)
+    void process_init_completion_cb(Process &proc)
     {
-        initialized_proc->suspend();
-        initialized_proc->mark_completed();
-        init_next_process();
+        proc.suspend();
+        remaining_process_inits--;
+        if (remaining_process_inits == 0) {
+            finish_process_init();
+        }
     }
 
     /** Called when a process exits during initialization. */
     void process_init_exit_cb(Process &proc, bool partition_empty)
     {
-        // if this is false, it means some other process exited,
-        //  this may happen for example on receiving SIGINT
-        if (!initialized_proc->is_running()) {
-            // end initialization of this process and move on to the next one
+        if (proc.needs_initialization()) {
+            // consider this process initialized
             process_init_completion_cb(proc);
         }
         // call original callback

test/0100-api.t

@@ -55,7 +55,7 @@ partitions:
 ')
 is "$out" \
 "init start
-init done
 init start
 init done
+init done
 <test>"

test_config/api_init_test.yaml

@@ -0,0 +1,15 @@
+windows:
+  - length: 200
+    slices:
+      - cpu: 0
+        sc_partition: SC1
+
+partitions:
+  - name: SC1
+    processes:
+      - cmd: ../build/src/tests/api-init-test
+        budget: 100
+        init: yes
+      - cmd: ../build/src/tests/api-init-test
+        budget: 100
+        init: yes