Even task consuming in ResizeProcessor.

dbms/src/Processors/ResizeProcessor.cpp

@@ -6,57 +6,84 @@ namespace DB
 
 ResizeProcessor::Status ResizeProcessor::prepare()
 {
-    auto cur_output = outputs.begin();
+    bool is_first_output = true;
+    auto output_end = current_output;
+
     bool all_outs_full_or_unneeded = true;
     bool all_outs_finished = true;
 
+    bool is_first_input = true;
+    auto input_end = current_input;
+
+    bool all_inputs_finished = true;
+
+    auto is_end_input = [&]() { return !is_first_input && current_input == input_end; };
+    auto is_end_output = [&]() { return !is_first_output && current_output == output_end; };
+
+    auto inc_current_input = [&]()
+    {
+        is_first_input = false;
+        ++current_input;
+
+        if (current_input == inputs.end())
+            current_input = inputs.begin();
+    };
+
+    auto inc_current_output = [&]()
+    {
+        is_first_output = false;
+        ++current_output;
+
+        if (current_output == outputs.end())
+            current_output = outputs.begin();
+    };
+
     /// Find next output where can push.
     auto get_next_out = [&, this]() -> OutputPorts::iterator
     {
-        while (cur_output != outputs.end())
+        while (!is_end_output())
         {
-            if (!cur_output->isFinished())
+            if (!current_output->isFinished())
             {
                 all_outs_finished = false;
 
-                if (cur_output->canPush())
+                if (current_output->canPush())
                 {
                     all_outs_full_or_unneeded = false;
-                    ++cur_output;
-                    return std::prev(cur_output);
+                    auto res_output = current_output;
+                    inc_current_output();
+                    return res_output;
                 }
             }
 
-            ++cur_output;
+            inc_current_output();
         }
 
-        return cur_output;
+        return current_output;
     };
 
-    auto cur_input = inputs.begin();
-    bool all_inputs_finished = true;
-
     /// Find next input from where can pull.
     auto get_next_input = [&, this]() -> InputPorts::iterator
     {
-        while (cur_input != inputs.end())
+        while (!is_end_input())
         {
-            if (!cur_input->isFinished())
+            if (!current_input->isFinished())
             {
                 all_inputs_finished = false;
 
-                cur_input->setNeeded();
-                if (cur_input->hasData())
+                current_input->setNeeded();
+                if (current_input->hasData())
                 {
-                    ++cur_input;
-                    return std::prev(cur_input);
+                    auto res_input = current_input;
+                    inc_current_input();
+                    return res_input;
                 }
             }
 
-            ++cur_input;
+            inc_current_input();
         }
 
-        return cur_input;
+        return current_input;
     };
 
     auto get_status_if_no_outputs = [&]() -> Status
@@ -97,21 +124,18 @@ ResizeProcessor::Status ResizeProcessor::prepare()
     /// Set all inputs needed in order to evenly process them.
     /// Otherwise, in case num_outputs < num_inputs and chunks are consumed faster than produced,
     ///   some inputs can be skipped.
-    auto set_all_unprocessed_inputs_needed = [&]()
-    {
-        for (; cur_input != inputs.end(); ++cur_input)
-            if (!cur_input->isFinished())
-                cur_input->setNeeded();
-    };
+//    auto set_all_unprocessed_inputs_needed = [&]()
+//    {
+//        for (; cur_input != inputs.end(); ++cur_input)
+//            if (!cur_input->isFinished())
+//                cur_input->setNeeded();
+//    };
 
-    while (cur_input != inputs.end() && cur_output != outputs.end())
+    while (!is_end_input() && !is_end_output())
     {
         auto output = get_next_out();
         if (output == outputs.end())
-        {
-            set_all_unprocessed_inputs_needed();
             return get_status_if_no_outputs();
-        }
 
         auto input = get_next_input();
         if (input == inputs.end())
@@ -120,11 +144,8 @@ ResizeProcessor::Status ResizeProcessor::prepare()
         output->push(input->pull());
     }
 
-    if (cur_output == outputs.end())
-    {
-        set_all_unprocessed_inputs_needed();
+    if (is_end_input())
         return get_status_if_no_outputs();
-    }
 
     /// cur_input == inputs_end()
     return get_status_if_no_inputs();

dbms/src/Processors/ResizeProcessor.h

@@ -21,14 +21,20 @@ class ResizeProcessor : public IProcessor
 {
 public:
     /// TODO Check that there is non zero number of inputs and outputs.
-    ResizeProcessor(Block header, size_t num_inputs, size_t num_outputs)
+    ResizeProcessor(const Block & header, size_t num_inputs, size_t num_outputs)
         : IProcessor(InputPorts(num_inputs, header), OutputPorts(num_outputs, header))
+        , current_input(inputs.begin())
+        , current_output(outputs.begin())
     {
     }
 
     String getName() const override { return "Resize"; }
 
     Status prepare() override;
+
+private:
+    InputPorts::iterator current_input;
+    OutputPorts::iterator current_output;
 };
 
 }