It sounds like what you want is an async service call that has a
return type? While there isn't support for this, you can always hack
together some sort of polling solution. For example:
struct JobStatus {
10: bool is_complete,
20: double percentage_complete,
30: i16 return_status
}
service ProcessingService {
/* requests the processing to begin, and returns the id of the job
that was launched */
i32 process(list<dataType> queue),
/* retrieves the latest status */
JobStatus getJobStatus(1:i32 job_id)
}
In your implementation, you have to spawn another thread to do the
work, of course, but this also lets you do a readers/writers solution
with either a single thread or threadpool devoted to data crunching.
-Ben
On May 28, 2008, at 4:46 PM, Benjamin Reed wrote:
Yes, I really need a success code. (The client is going to be
waiting for it.)
I want to do exactly what you are proposing except that I want to
queue a
completion function into dataToInsert as well, so that the
insertWorker can
send back the response to the rpc to the client when the commit
completes.
thanx
ben
On Wednesday 28 May 2008 12:01:49 Philip Fung wrote:
Does your calling function really need to know if the insert was
successful? If you can do without this extra overhead, then I think
the best way to do this is to place the insert request on a queue and
free up the RPC request immediately rather than wait for the inserts
to batch up and complete.
So some skeleton code would be:
static LinkedBlockingQueue<dataType> dataToInsert = new
LinkedBlockingQueue<dataType>(); //java.util.concurrent
static int INSERT_TIME_THRESHOLD = 3600;
static int INSERT_SIZE_THRESHOLD = 1000;
// thrift-accessible function
public void insert(dataType data) {
this.dataToInsert.add(data); //thread-safe
}
// worker threads
private static class insertWorker extends Thread {
public void run() {
ArrayList<dataType> dataToInsertWorker = new
ArrayList<dataType>();
while (true) {
dataToInsertWorker.add(this.dataToInsert.take()); //blocks
if ((dataToInsertWorker.size() >
INSERT_SIZE_THRESHOLD) ||
(dataToInsertWorker.size() > 1 &&
(System.currentTimeMillis() -
lastInsertTime) > INSERT_TIME_THRESHOLD)) {
// insert into DB here
lastInsertTime =
System.currentTimeMillis();
}
}
}
}
--------------------------
Philip Fung
Engineering
Facebook, Inc.
[EMAIL PROTECTED]
On May 28, 2008, at 11:46 AM, Ben Maurer wrote:
Hey,
Usually, when writing stuff for thrift, I've found it's best to
create an
object that takes parameters:
FooReturn doFoo(1: FooArgs args);
For the return value, this is pretty critical because thrift doesn't
allow
you to return multiple values. For the arguments, I've found that
even
though thrift can support multiple arguments, doing this makes it
easier
(eg, you can serialize args and log it).
So for this kind of API I'd just take the args value insert it
into a
queue. It does require a bit of work for each function, however, you
can
also do stuff like validate the request and raise an exception if
you know
the insert will fail.
-b
On Wed, 28 May 2008, Benjamin Reed wrote:
Could I get a pointer to how to deal with the following scenario:
I have a Java server using thrift. There are potentially hundreds
of clients
sending hundreds of requests at a time. The server receives a
request,
batches it up with other pending requests, processes a batch at a
time, and
then generates the responses when the batch finishes.
For example, clients A, B, and C, are each sending up records to be
inserted
into a database. The clients are sending up 1000 requests per
second. The
server will grab some number, lets say 100 requests at a time,
insert them
into the database, issue a commit, and send back successful
responses. Doing
batch commits of 100 requests at a time allows the server to keep
up with the
clients. Committing each request individually would be too slow.
So, in my Java server, how do I get an RPC request and then put it
on a
completion list so that I can free up the thread for the next RPC
call and
complete the RPC when I do the batch processing?
thanx
ben
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