binderThroughputTest: gather servers right away

Start gathering servers upon worker creation. Don't wait until signaled
by test. This should allow all clients to start transactions at a better
coordinated time.

Change-Id: I4568eb55fc9ce18839c1e5592a722a0284987745
Test: Ran a benchmark on cuttlefish, and it did not get stuck
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Co-developed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>

Author: Carlos Llamas

libs/binder/tests/binderThroughputTest.cpp

@@ -220,6 +220,9 @@ void worker_fx(int num,
         workers.push_back(serviceMgr->waitForService(generateServiceName(i)));
     }
 
+    p.signal();
+    p.wait();
+
     // Run the benchmark if client
     ProcResults results(iterations);
 
@@ -300,8 +303,15 @@ void run_main(int iterations,
         pipes.push_back(make_worker(i, iterations, workers, payload_size, cs_pair));
     }
     wait_all(pipes);
+    // All workers have now been spawned and added themselves to service
+    // manager. Signal each worker to obtain a handle to the server workers from
+    // servicemanager.
+    signal_all(pipes);
+    // Wait for each worker to finish obtaining a handle to all server workers
+    // from servicemanager.
+    wait_all(pipes);
 
-    // Run the workers and wait for completion.
+    // Run the benchmark and wait for completion.
     chrono::time_point<chrono::high_resolution_clock> start, end;
     cout << "waiting for workers to complete" << endl;
     start = chrono::high_resolution_clock::now();