Merge branch 'master' into dev

clin99 · clin99 · commit a78edab82723 · 2019-08-30T13:49:49.000-06:00
diff --git a/README.md b/README.md
@@ -916,7 +916,7 @@ Cpp-Taskflow is being actively developed and contributed by the following people
 - [Paolo Bolzoni](https://github.com/paolobolzoni) helped remove extraneous semicolons to suppress extra warning during compilation and contributed to a dataflow example
 - [Pursche](https://github.com/Pursche) fixed compilation warning on Microsoft Visual Studio
 - [KingDuckZ][KingDuckZ] helped discover the memory leak in the memory allocator used in graph and topology
-- [mrogez-yseop](https://github.com/mrogez-yseop) helped fix the missing comma in outputting the execution timeline JSON from the observer
+- [mrogez-yseop](https://github.com/mrogez-yseop) helped fix the missing comma in outputting the execution timeline JSON from the observer and the composition of an empty taskflow.
 - [Sztergbaum Roman](https://github.com/Milerius) replaced the error-prone global setting in cmake with project-specific targets
 
 Meanwhile, we appreciate the support from many organizations for our development on Cpp-Taskflow.
diff --git a/benchmark/matrix_multiplication/taskflow.cpp b/benchmark/matrix_multiplication/taskflow.cpp
@@ -7,48 +7,41 @@ void matrix_multiplication_taskflow(unsigned num_threads) {
   tf::Executor executor(num_threads); 
   tf::Taskflow taskflow;
 
-  std::vector<tf::Task> tasks; 
-  tasks.reserve(4*N);
   auto sync = taskflow.emplace([](){});
 
   for(int i=0; i<N; ++i) {
-    tasks[i] = taskflow.emplace([&, i=i](){
+    taskflow.emplace([&, i=i](){
       for(int j=0; j<N; ++j) {
         a[i][j] = i + j;
       }
-    });
-    tasks[i].precede(sync);
+    }).precede(sync);
   }
 
   for(int i=0; i<N; ++i) {
-    tasks[i+N] = taskflow.emplace([&, i=i](){
+    taskflow.emplace([&, i=i](){
       for(int j=0; j<N; ++j) {
         b[i][j] = i * j;
       }
-    });
-    tasks[i+N].precede(sync);
+    }).precede(sync);
   }
-  tasks.clear();
 
   for(int i=0; i<N; ++i) {
-    tasks[i+2*N] = taskflow.emplace([&, i=i](){
+    taskflow.emplace([&, i=i](){
       for(int j=0; j<N; ++j) {
         c[i][j] = 0;;
       }
-    });
-    tasks[i+2*N].precede(sync);
+    }).precede(sync);
   }
-  tasks.clear();
 
   for(int i=0; i<N; ++i) {
-    tasks[i+3*N] = taskflow.emplace([&, i=i](){
+    auto t = taskflow.emplace([&, i=i](){
       for(int j=0; j<N; ++j) {
         for(int k=0; k<N; k++) {
           c[i][j] += a[i][k] * b[k][j];
         }
       }
     });
-    sync.precede(tasks[i+3*N]);
+    sync.precede(t);
   }
 
   executor.run(taskflow).get(); 
diff --git a/taskflow/core/executor.hpp b/taskflow/core/executor.hpp
@@ -510,7 +510,7 @@ inline void Executor::_schedule_unsync(
 ) const {
   
   // module node need another initialization
-  if(node->_module != nullptr && !node->is_spawned()) {
+  if(node->_module != nullptr && !node->_module->empty() && !node->is_spawned()) {
     _init_module_node_unsync(node, stack);
   }
 
@@ -526,7 +526,7 @@ inline void Executor::_schedule_unsync(
   // here we guarantee to run by a thread so no need to cache the
   // size from nodes
   for(auto node : nodes) {
-    if(node->_module != nullptr && !node->is_spawned()) {
+    if(node->_module != nullptr && !node->_module->empty() && !node->is_spawned()) {
       _init_module_node_unsync(node, stack);
     }
     stack.push(node);
@@ -541,7 +541,7 @@ inline void Executor::_schedule(Node* node, bool bypass) {
   assert(_workers.size() != 0);
   
   // module node need another initialization
-  if(node->_module != nullptr && !node->is_spawned()) {
+  if(node->_module != nullptr && !node->_module->empty() && !node->is_spawned()) {
     _init_module_node(node);
   }
   
@@ -582,7 +582,7 @@ inline void Executor::_schedule(PassiveVector<Node*>& nodes) {
   }
 
   for(auto node : nodes) {
-    if(node->_module != nullptr && !node->is_spawned()) {
+    if(node->_module != nullptr && !node->_module->empty() && !node->is_spawned()) {
       _init_module_node(node);
     }
   }

Original file line number	Diff line number	Diff line change
`@@ -510,7 +510,7 @@ inline void Executor::_schedule_unsync(`
`510`	`510`	`) const {`
`511`	`511`
`512`	`512`	`// module node need another initialization`
`513`		`- if(node->_module != nullptr && !node->is_spawned()) {`
	`513`	`+ if(node->_module != nullptr && !node->_module->empty() && !node->is_spawned()) {`
`514`	`514`	`_init_module_node_unsync(node, stack);`
`515`	`515`	`}`
`516`	`516`
`@@ -526,7 +526,7 @@ inline void Executor::_schedule_unsync(`
`526`	`526`	`// here we guarantee to run by a thread so no need to cache the`
`527`	`527`	`// size from nodes`
`528`	`528`	`for(auto node : nodes) {`
`529`		`- if(node->_module != nullptr && !node->is_spawned()) {`
	`529`	`+ if(node->_module != nullptr && !node->_module->empty() && !node->is_spawned()) {`
`530`	`530`	`_init_module_node_unsync(node, stack);`
`531`	`531`	`}`
`532`	`532`	`stack.push(node);`
`@@ -541,7 +541,7 @@ inline void Executor::_schedule(Node* node, bool bypass) {`
`541`	`541`	`assert(_workers.size() != 0);`
`542`	`542`
`543`	`543`	`// module node need another initialization`
`544`		`- if(node->_module != nullptr && !node->is_spawned()) {`
	`544`	`+ if(node->_module != nullptr && !node->_module->empty() && !node->is_spawned()) {`
`545`	`545`	`_init_module_node(node);`
`546`	`546`	`}`
`547`	`547`
`@@ -582,7 +582,7 @@ inline void Executor::_schedule(PassiveVector<Node*>& nodes) {`
`582`	`582`	`}`
`583`	`583`
`584`	`584`	`for(auto node : nodes) {`
`585`		`- if(node->_module != nullptr && !node->is_spawned()) {`
	`585`	`+ if(node->_module != nullptr && !node->_module->empty() && !node->is_spawned()) {`
`586`	`586`	`_init_module_node(node);`
`587`	`587`	`}`
`588`	`588`	`}`