From: Mikko Rasa <tdb@tdb.fi>
Date: Thu, 9 Oct 2014 17:46:37 +0000 (+0300)
Subject: Add utility class for executing chains of tasks
X-Git-Url: http://git.tdb.fi/?p=builder.git;a=commitdiff_plain;h=b53686e4824eb15d00d1539cc9672cf2b5a5cc82

Add utility class for executing chains of tasks
---

diff --git a/source/chainedtask.cpp b/source/chainedtask.cpp
new file mode 100644
index 0000000..066dc22
--- /dev/null
+++ b/source/chainedtask.cpp
@@ -0,0 +1,75 @@
+#include "chainedtask.h"
+
+using namespace std;
+
+ChainedTask::ChainedTask(Task *t):
+	current(0),
+	final_status(RUNNING)
+{
+	add_task(t);
+}
+
+ChainedTask::~ChainedTask()
+{
+	for(vector<Task *>::iterator i=tasks.begin(); i!=tasks.end(); ++i)
+		delete *i;
+}
+
+void ChainedTask::add_task(Task *t)
+{
+	tasks.push_back(t);
+}
+
+string ChainedTask::get_command() const
+{
+	string cmd;
+	for(vector<Task *>::const_iterator i=tasks.begin(); i!=tasks.end(); ++i)
+	{
+		if(i!=tasks.begin())
+			cmd += '\n';
+		cmd += (*i)->get_command();
+	}
+	return cmd;
+}
+
+void ChainedTask::start()
+{
+	prepare();
+
+	current = 0;
+	tasks[current]->start();
+}
+
+Task::Status ChainedTask::check()
+{
+	while(current<tasks.size() && !process(tasks[current]->check())) ;
+
+	return final_status;
+}
+
+Task::Status ChainedTask::wait()
+{
+	while(current<tasks.size() && !process(tasks[current]->wait())) ;
+
+	return final_status;
+}
+
+bool ChainedTask::process(Status sub_status)
+{
+	if(sub_status==SUCCESS && current+1<tasks.size())
+	{
+		// The task succeeded and there's more to run
+		++current;
+		tasks[current]->start();
+		return true;
+	}
+
+	if(sub_status!=RUNNING)
+	{
+		// The task is not running anymore and either failed or was the last one
+		current = tasks.size();
+		final_status = sub_status;
+	}
+
+	return false;
+}
diff --git a/source/chainedtask.h b/source/chainedtask.h
new file mode 100644
index 0000000..2014f02
--- /dev/null
+++ b/source/chainedtask.h
@@ -0,0 +1,32 @@
+#ifndef CHAINEDTASK_H_
+#define CHAINEDTASK_H_
+
+#include <vector>
+#include "task.h"
+
+/**
+Runs multiple tasks as one unit, one after the other.  Execution of the chain
+will stop if any of the component tasks terminates with an error.
+*/
+class ChainedTask: public Task
+{
+private:
+	std::vector<Task *> tasks;
+	unsigned current;
+	Status final_status;
+
+public:
+	ChainedTask(Task *);
+	~ChainedTask();
+
+	void add_task(Task *);
+
+	virtual std::string get_command() const;
+	virtual void start();
+	virtual Status check();
+	virtual Status wait();
+private:
+	bool process(Status);
+};
+
+#endif