New signal: Activity::on_veto, to detect when an activity fails to start

diff --git a/ChangeLog b/ChangeLog
index c71fe26..9ef1ed5 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -2,8 +2,9 @@
 
 SimGrid (3.29.1) NOT RELEASED YET (v3.30 expected December 21. 2021, 15:59 UTC)
 
-Engine:
- - New function: run_until(date) allowing to split the simulation.
+S4U:
+ - New function: Engine::run_until(date), to split the simulation.
+ - New signal: Activity::on_veto, to detect when an activity fails to start.
 
 SMPI:
  - Dynamic costs for MPI operations: New API to allow users to dynamically

diff --git a/examples/cpp/exec-dependent/s4u-exec-dependent.cpp b/examples/cpp/exec-dependent/s4u-exec-dependent.cpp
index db155eb..ada7e5e 100644 (file)
--- a/examples/cpp/exec-dependent/s4u-exec-dependent.cpp
+++ b/examples/cpp/exec-dependent/s4u-exec-dependent.cpp
@@ -21,7 +21,7 @@ static void worker()
   pending_execs.push_back(first_parent);
   simgrid::s4u::ExecPtr second_parent = simgrid::s4u::this_actor::exec_init(2 * computation_amount);
   pending_execs.push_back(second_parent);
-  simgrid::s4u::ExecPtr child = simgrid::s4u::this_actor::exec_init(computation_amount);
+  simgrid::s4u::ExecPtr child = simgrid::s4u::Exec::init()->set_flops_amount(computation_amount);
   pending_execs.push_back(child);
 
   // Name the activities (for logging purposes only)
@@ -54,6 +54,21 @@ int main(int argc, char* argv[])
 
   simgrid::s4u::Actor::create("worker", e.host_by_name("Fafard"), worker);
 
+  simgrid::s4u::Activity::on_veto.connect([&e](simgrid::s4u::Activity& a) {
+    auto& exec = static_cast<simgrid::s4u::Exec&>(a);
+
+    // First display the situation
+    XBT_INFO("Activity '%s' vetoed. Dependencies: %s; Ressources: %s", exec.get_cname(),
+             (exec.dependencies_solved() ? "solved" : "NOT solved"),
+             (exec.is_assigned() ? "assigned" : "NOT assigned"));
+
+    // In this simple case, we just assign the child task to a resource when its dependencies are solved
+    if (exec.dependencies_solved() && not exec.is_assigned()) {
+      XBT_INFO("Activity %s's dependencies are resolved. Let's assign it to Fafard.", exec.get_cname());
+      exec.set_host(e.host_by_name("Fafard"));
+    }
+  });
+
   e.run();
 
   XBT_INFO("Simulation time %g", simgrid::s4u::Engine::get_clock());

diff --git a/examples/cpp/exec-dependent/s4u-exec-dependent.tesh b/examples/cpp/exec-dependent/s4u-exec-dependent.tesh
index c27d3ff..a376e10 100644 (file)
--- a/examples/cpp/exec-dependent/s4u-exec-dependent.tesh
+++ b/examples/cpp/exec-dependent/s4u-exec-dependent.tesh
@@ -1,10 +1,12 @@
 #!/usr/bin/env tesh
 
-! output sort
 $ ${bindir:=.}/s4u-exec-dependent ${platfdir}/small_platform.xml --log=s4u_activity.t:verbose "--log=root.fmt:[%10.6r]%e(%i:%a@%h)%e%m%n"
+> [  0.000000] (1:worker@Fafard) Activity 'child' vetoed. Dependencies: NOT solved; Ressources: NOT assigned
 > [  2.000000] (1:worker@Fafard) Remove a dependency from 'parent 1' on 'child'
 > [  2.000000] (1:worker@Fafard) Exec 'parent 1' is complete
 > [  3.000000] (1:worker@Fafard) Remove a dependency from 'parent 2' on 'child'
+> [  3.000000] (1:worker@Fafard) Activity 'child' vetoed. Dependencies: solved; Ressources: NOT assigned
+> [  3.000000] (1:worker@Fafard) Activity child's dependencies are resolved. Let's assign it to Fafard.
 > [  3.000000] (1:worker@Fafard) 'child' is assigned to a resource and all dependencies are solved. Let's start
 > [  3.000000] (1:worker@Fafard) Exec 'parent 2' is complete
 > [  4.000000] (1:worker@Fafard) Exec 'child' is complete

diff --git a/include/simgrid/s4u/Activity.hpp b/include/simgrid/s4u/Activity.hpp
index 0e165e7..ff42c98 100644 (file)
--- a/include/simgrid/s4u/Activity.hpp
+++ b/include/simgrid/s4u/Activity.hpp
@@ -36,12 +36,13 @@ public:
   // enum class State { ... }
   XBT_DECLARE_ENUM_CLASS(State, INITED, STARTING, STARTED, FAILED, CANCELED, FINISHED);
 
+  virtual bool is_assigned() const = 0;
+  virtual bool dependencies_solved() const { return dependencies_.empty(); }
+
 protected:
   Activity()  = default;
   virtual ~Activity() = default;
 
-  virtual bool is_assigned() const = 0;
-  virtual bool dependencies_solved() { return dependencies_.empty(); }
   virtual void complete(Activity::State state)
   {
     state_ = state;
@@ -88,12 +89,18 @@ protected:
   }
 
 public:
+  /*! Signal fired each time that the activity fails to start because of a veto (e.g., unsolved dependency or no
+   * resource assigned) */
+  static xbt::signal<void(Activity&)> on_veto;
+
   void vetoable_start()
   {
     state_ = State::STARTING;
     if (dependencies_solved() && is_assigned()) {
       XBT_CVERB(s4u_activity, "'%s' is assigned to a resource and all dependencies are solved. Let's start", get_cname());
       start();
+    } else {
+      on_veto(*this);
     }
   }
 

diff --git a/include/simgrid/s4u/Exec.hpp b/include/simgrid/s4u/Exec.hpp
index 3aa1400..e6b18d0 100644 (file)
--- a/include/simgrid/s4u/Exec.hpp
+++ b/include/simgrid/s4u/Exec.hpp
@@ -46,7 +46,9 @@ public:
   Exec(Exec const&) = delete;
   Exec& operator=(Exec const&) = delete;
 #endif
+  /*! Signal fired each time that an execution actually starts (no veto) */
   static xbt::signal<void(Exec const&)> on_start;
+  /*! Signal fired each time that an execution terminates (either normally, cancelled or failed) */
   static xbt::signal<void(Exec const&)> on_completion;
 
   static ExecPtr init();

diff --git a/src/s4u/s4u_Activity.cpp b/src/s4u/s4u_Activity.cpp
index d07506a..000e1b5 100644 (file)
--- a/src/s4u/s4u_Activity.cpp
+++ b/src/s4u/s4u_Activity.cpp
@@ -19,6 +19,8 @@ XBT_LOG_NEW_DEFAULT_SUBCATEGORY(s4u_activity, s4u, "S4U activities");
 namespace simgrid {
 namespace s4u {
 
+xbt::signal<void(Activity&)> Activity::on_veto;
+
 void Activity::wait_until(double time_limit)
 {
   double now = Engine::get_clock();