Developing and running applications that use the DPS Toolkit

Note regarding fusing Java operators: Fusing two or more Java operators that utilize the Java DPS API requires that each operator have the same class path and the @SharedLoader annotation in its class definition. For example:

PrimitiveOperator(name="MyJavaOperator", namespace="com.ibm.demo",  description="Java Operator MyJavaOperator")
@SharedLoader(true)
public class MyJavaOperator extends AbstractOperator {
	...
}

rstring dummyRstring = "";
uint32 dummyUint32 = 0u;
mutable uint64 err = 0ul;
mutable uint64 dbStore_handle = 0ul;
dbStore_handle = dpsCreateStore("myDBStore1", dummyRstring, dummyUint32, err);

if (err == 0ul ) { //no error occurred
	 //create lock for the store
	mutable uint64 lock_id = dlCreateOrGetLock("My db store lock", err);
	// Acquire the newly created lock, specifying a lease time and maximum time to wait to acquire the lock.
	float64 max_wait = 10.0;
	float64 lease_time = 10.0;
	dlAcquireLock(lock_id, lease_time, max_wait, err);
	//add a key/value pair to the store
	mutable boolean result = true;
	rstring key = "IBM";
	uint32 value = 399;
	err = 0ul;
	result = dpsPut(dbStore_handle, key, value, err);
	
	if (err != 0ul) {
		//use  dpsGetLastStoreErrorCode() and  dpsGetLastStoreErrorString() as needed
	}
	// finished our store operations, release the lock
	err = 0ul;
	dlReleaseLock(lock_id, err);	
}

StoreFactory sf = DistributedStores.getStoreFactory();
Store store = null;

try {
   //specify the SPL types for the keys and values in the store
   String keyType = "rstring";
   String valueType = "int32";
   store = sf.createOrGetStore("Java Test Store1", keyType, valueType);
} catch (StoreFactoryException sfe) {
	// use	sfe.getErrorCode() and  sfe.getErrorMessage()) for more info
}

...
//once ready to access the store,
//get the lock for the store, may have previously been created
   LockFactory lf = DistributedLocks.getLockFactory(); 
   Lock myLock = lf.createOrGetLock("Lock_For_Test_Store1");

// Acquire the lock
try {
 	myLock.acquireLock();
} catch (LockException le) {
	System.out.print("Unable to acquire the lock named 'Lock_For_Test_Store1'");
	System.out.println(" Error = " + le.getErrorCode() + ", Error msg = " + le.getErrorMessage());
    throw le;
}

//perform store operations
store.put("IBM", 39);
store.put("Lenovo", 50);
//release the lock  when finished
myLock.releaseLock();

In addition, there are functions that can be called when an error occurs to return the last error code and a message describing the error. The correct function to call after an operation depends on the operation that was last executed.

• For errors relating to the store functions, use dpsGetLastStoreErrorCode() and dpsGetLastStoreErrorString().
• For errors related to the TTL functions, use dpsGetLastStoreErrorCodeTTL() and dpsGetLastStoreErrorStringTTL().
• For locking related errors, use dlGetLastDistributedLockErrorCode() and dlGetLastDistributedLockErrorString().

mutable uint64 err = 0ul;
mutable uint64 lock_id = dlCreateOrGetLock("My Sentinel Lock1", err);

if (err != 0ul) {
	rstring msg = dlGetLastDistributedLockErrorString();
	uint64 rc = dlGetLastDistributedLockErrorCode();
	printStringLn("Error creating lock, rc = " + (rstring)(rc) + ", msg =" + msg );
}