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commented machine utils

This commit is contained in:
David Ribeiro Alves 2012-03-22 03:46:22 +00:00
parent 6b4a4c6054
commit 582423bd2d
1 changed files with 67 additions and 30 deletions
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51
labs/virtualbox/src/main/java/org/jclouds/virtualbox/util/MachineUtils.java
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@ -45,7 +45,7 @@ import com.google.inject.Inject;
/**
* Utilities for executing functions on a VirtualBox machine.
*
* @author Adrian Cole, Mattias Holmqvist, Andrea Turli
* @author Adrian Cole, Mattias Holmqvist, Andrea Turli, David Alves
*/
@Singleton
@ -101,10 +101,34 @@ public class MachineUtils {
});
}
/**
* Locks the machine and executes the given function using the machine matching the given id.
* The machine is write locked and modifications to the session that reflect on the machine can be done safely.
* <p/>
* Unlocks the machine before returning.
*
* @param machineId
* the id of the machine
* @param function
* the function to execute
* @return the result from applying the function to the machine.
*/
public <T> T writeLockMachineAndApplyToSession(final String machineId, final Function<ISession, T> function) {
return lockSessionOnMachineAndApply(machineId, LockType.Write, function);
}
/**
* Locks the machine and executes the given function using the machine matching the given id.
* The machine is read locked, which means that settings can be read safely (but not changed) by function.
* <p/>
* Unlocks the machine before returning.
*
* @param machineId
* the id of the machine
* @param function
* the function to execute
* @return the result from applying the function to the machine.
*/
public <T> T readLockMachineAndApply(final String machineId, final Function<IMachine, T> function) {
return lockSessionOnMachineAndApply(machineId, LockType.Shared, new Function<ISession, T>() {
@ -121,6 +145,18 @@ public class MachineUtils {
});
}
/**
* Locks the machine and executes the given function to the session using the machine matching the given id.
* The machine is read locked, which means that settings can be read safely (but not changed) by function.
* <p/>
* Unlocks the machine before returning.
*
* @param machineId
* the id of the machine
* @param function
* the function to execute
* @return the result from applying the function to the machine.
*/
public <T> T readLockMachineAndApplyToSession(final String machineId, final Function<ISession, T> function) {
return lockSessionOnMachineAndApply(machineId, LockType.Shared, function);
}
@ -132,6 +168,9 @@ public class MachineUtils {
* <p/>
* Unlocks the machine before returning.
*
* Tries to obtain a lock 5 times before giving up waiting 1 sec between tries. When no machine
* is found null is returned.
*
* @param type
* the kind of lock to use when initially locking the machine.
* @param machineId
@ -141,7 +180,6 @@ public class MachineUtils {
* @return the result from applying the function to the session.
*/
private <T> T lockSessionOnMachineAndApply(String machineId, LockType type, Function<ISession, T> function) {
try {
int retries = 5;
int count = 0;
ISession session;
@ -159,8 +197,8 @@ public class MachineUtils {
count++;
logger.warn("Could not lock machine (try %i of %i). Error: %s", retries, count, e.getMessage());
if (count == retries) {
throw new RuntimeException(String.format("error locking %s with %s lock: %s", machineId,
type, e.getMessage()), e);
throw new RuntimeException(String.format("error locking %s with %s lock: %s", machineId, type,
e.getMessage()), e);
}
try {
Thread.sleep(1000L);
@ -170,12 +208,11 @@ public class MachineUtils {
}
try {
return function.apply(session);
} finally {
session.unlockMachine();
}
} catch (VBoxException e) {
throw new RuntimeException(String.format("error applying %s to %s with %s lock: %s", function, machineId,
type, e.getMessage()), e);
} finally {
session.unlockMachine();
}
}