fix: remove inline GC and schedule a background task instead (#1610)

* fix: remove inline GC and set a default value of gc interval

- remove inline GC
- add a default value of GC interval
- run the GC periodically by default with the default value if no interval provided
- generate GC tasks with a random delay(0-30s) between
- add IsReady() method to scheduler.TaskGenerator interface

Signed-off-by: Andreea-Lupu <andreealupu1470@yahoo.com>

* ci: add test for gc with short interval

Signed-off-by: Andreea-Lupu <andreealupu1470@yahoo.com>

---------

Signed-off-by: Andreea-Lupu <andreealupu1470@yahoo.com>

pkg/scheduler/README.md

@@ -1,7 +1,7 @@
 # How to submit a Generator to the scheduler
 
 ## What is a generator and how should it be implemented?
-In order to create a new generator (which will generate new tasks one by one) and add it to the scheduler there are 3 methods which should be implemented:
+In order to create a new generator (which will generate new tasks one by one) and add it to the scheduler there are 4 methods which should be implemented:
 1. ***GenerateTask() (Task, error)***
     ```
     This method should implement the logic for generating a new task. 
@@ -12,7 +12,11 @@ In order to create a new generator (which will generate new tasks one by one) an
     ```
     This method should return true after the generator finished all the work and has no more tasks to generate.
     ```
-3. ***Reset()***
+3. ***IsReady() bool***
+    ```
+    This method should return true if the generator is ready to generate a new task and should be used when it is needed to generate tasks with some delay between.
+    ```
+4. ***Reset()***
     ```
     When this method is called the generator should reset to its initial state.
     After the generator is reset, it will generate new tasks as if it hadn't been used before.

pkg/scheduler/scheduler.go

@@ -284,6 +284,7 @@ const (
 type TaskGenerator interface {
 	Next() (Task, error)
 	IsDone() bool
+	IsReady() bool
 	Reset()
 }
 
@@ -351,6 +352,10 @@ func (gen *generator) getState() state {
 		}
 	}
 
+	if !gen.taskGenerator.IsReady() {
+		return waiting
+	}
+
 	return ready
 }
 

pkg/scheduler/scheduler_test.go

@@ -56,6 +56,10 @@ func (g *generator) IsDone() bool {
 	return g.done
 }
 
+func (g *generator) IsReady() bool {
+	return true
+}
+
 func (g *generator) Reset() {
 	g.done = false
 	g.step = 0
@@ -79,6 +83,10 @@ func (g *shortGenerator) IsDone() bool {
 	return g.done
 }
 
+func (g *shortGenerator) IsReady() bool {
+	return true
+}
+
 func (g *shortGenerator) Reset() {
 	g.done = true
 	g.step = 0