Throw Python exception if plasma store cannot create new object. (#162)

* Propagate error messages through plasma create.

* Use custom exception types instead of exception messages.

src/plasma/test/test.py

@@ -107,8 +107,78 @@ class TestPlasmaClient(unittest.TestCase):
       self.plasma_client.create(object_id, length, generate_metadata(length))
       try:
         val = self.plasma_client.create(object_id, length, generate_metadata(length))
-      except Exception:
+      except plasma.plasma_object_exists_error as e:
         pass
+      else:
+        self.assertTrue(False)
+
+  def test_store_full(self):
+    # The store is started with 1GB, so make sure that create throws an
+    # exception when it is full.
+    def assert_create_raises_plasma_full(unit_test, size):
+      partial_size = np.random.randint(size)
+      try:
+        _, memory_buffer, _ = create_object(unit_test.plasma_client, partial_size, size - partial_size)
+      except plasma.plasma_out_of_memory_error as e:
+        pass
+      else:
+        # For some reason the above didn't throw an exception, so fail.
+        unit_test.assertTrue(False)
+
+    # Create a list to keep some of the buffers in scope.
+    memory_buffers = []
+    _, memory_buffer, _ = create_object(self.plasma_client, 9 * 10 ** 8, 0)
+    memory_buffers.append(memory_buffer)
+    # Remaining space is 10 ** 8. Make sure that we can't create an object of
+    # size 10 ** 8 + 1, but we can create one of size 10 ** 8.
+    assert_create_raises_plasma_full(self, 10 ** 8 + 1)
+    _, memory_buffer, _ = create_object(self.plasma_client, 10 ** 8, 0)
+    del memory_buffer
+    _, memory_buffer, _ = create_object(self.plasma_client, 10 ** 8, 0)
+    del memory_buffer
+    assert_create_raises_plasma_full(self, 10 ** 8 + 1)
+
+    _, memory_buffer, _ = create_object(self.plasma_client, 9 * 10 ** 7, 0)
+    memory_buffers.append(memory_buffer)
+    # Remaining space is 10 ** 7.
+    assert_create_raises_plasma_full(self, 10 ** 7 + 1)
+
+    _, memory_buffer, _ = create_object(self.plasma_client, 9 * 10 ** 6, 0)
+    memory_buffers.append(memory_buffer)
+    # Remaining space is 10 ** 6.
+    assert_create_raises_plasma_full(self, 10 ** 6 + 1)
+
+    _, memory_buffer, _ = create_object(self.plasma_client, 9 * 10 ** 5, 0)
+    memory_buffers.append(memory_buffer)
+    # Remaining space is 10 ** 5.
+    assert_create_raises_plasma_full(self, 10 ** 5 + 1)
+
+    _, memory_buffer, _ = create_object(self.plasma_client, 9 * 10 ** 4, 0)
+    memory_buffers.append(memory_buffer)
+    # Remaining space is 10 ** 4.
+    assert_create_raises_plasma_full(self, 10 ** 4 + 1)
+
+    _, memory_buffer, _ = create_object(self.plasma_client, 9 * 10 ** 3, 0)
+    memory_buffers.append(memory_buffer)
+    # Remaining space is 10 ** 3.
+    assert_create_raises_plasma_full(self, 10 ** 3 + 1)
+
+    _, memory_buffer, _ = create_object(self.plasma_client, 9 * 10 ** 2, 0)
+    memory_buffers.append(memory_buffer)
+    # Remaining space is 10 ** 2.
+    assert_create_raises_plasma_full(self, 10 ** 2 + 1)
+
+    _, memory_buffer, _ = create_object(self.plasma_client, 9 * 10 ** 1, 0)
+    memory_buffers.append(memory_buffer)
+    # Remaining space is 10 ** 1.
+    assert_create_raises_plasma_full(self, 10 ** 1 + 1)
+
+    _, memory_buffer, _ = create_object(self.plasma_client, 9 * 10 ** 0, 0)
+    memory_buffers.append(memory_buffer)
+    # Remaining space is 10 ** 0.
+    assert_create_raises_plasma_full(self, 10 ** 0 + 1)
+
+    _, memory_buffer, _ = create_object(self.plasma_client, 1, 0)
 
   def test_contains(self):
     fake_object_ids = [random_object_id() for _ in range(100)]