How can I call another method after all `FutureTask` have finished their computations? - listener

Question

I have the following method that creates and deploys applications in different PaaS:
private void deployModulesInPaaS() {
ExecutorService executor = Executors.newFixedThreadPool(listModules
.size());
ModuleParsed mod;
for (Iterator<ModuleParsed> iterator = listModules.iterator(); iterator
.hasNext();) {
mod = (ModuleParsed) iterator.next();
try {
switch (mod.getId_paas()) {
case 1:
GAEDeployer gaeDeployer = new GAEDeployer(mod.getId_paas(),
mod.getId_component(), "//whatever/path");
FutureTask<URI> gaeFuture = new FutureTask<URI>(gaeDeployer);
executor.execute(gaeFuture);
mod.setDeployedURI(gaeFuture.get());
break;
case 2:
AzureDeployer azureDeployer = new AzureDeployer(
"subscription", "path_certificate", "password",
"storageAccountName", "storageAccountKey");
FutureTask<URI> azureFuture = new FutureTask<URI>(
azureDeployer);
executor.execute(azureFuture);
mod.setDeployedURI(azureFuture.get());
break;
default:
System.out.println("The PaaS identifier of module "
+ mod.getId_component() + " is unknown.");
break;
}
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
}
}
How can I call another method once all FutureTask have finished their computations?
I have read about Command pattern and about Listener but I'm not sure if these would be the right ones nor how to implement them in this case.

Answer 1

You really need ListenableFuture, please search the keyword "fan-in" on this page.
Another way with CountDownLatch and overriding FutureTask.done(),not recommended:
private void deployModulesInPaaS() {
CountDownLatch countDownLatch = new CountDownLatch(listModules.size());
ExecutorService executor = Executors.newFixedThreadPool(listModules
.size());
ModuleParsed mod;
for (Iterator<ModuleParsed> iterator = listModules.iterator(); iterator
.hasNext();) {
mod = (ModuleParsed) iterator.next();
try {
switch (mod.getId_paas()) {
case 1:
GAEDeployer gaeDeployer = new GAEDeployer(mod.getId_paas(),
mod.getId_component(), "//whatever/path");
FutureTask<URI> gaeFuture = new FutureTask<URI>(gaeDeployer) {
#Override
protected void done() {
super.done();
countDownLatch.countDown();
}
};
executor.execute(gaeFuture);
mod.setDeployedURI(gaeFuture.get());
break;
case 2:
AzureDeployer azureDeployer = new AzureDeployer(
"subscription", "path_certificate", "password",
"storageAccountName", "storageAccountKey");
FutureTask<URI> azureFuture = new FutureTask<URI>(
azureDeployer) {
#Override
protected void done() {
super.done();
countDownLatch.countDown();
}
};
executor.execute(azureFuture);
mod.setDeployedURI(azureFuture.get());
break;
default:
System.out.println("The PaaS identifier of module "
+ mod.getId_component() + " is unknown.");
break;
}
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
}
countDownLatch.await();
// do finally
}