Adding documentation for the terminate() method on the Connection classes.

Author: MarkDuckworth

packages/firestore/src/platform/node/grpc_connection.ts

@@ -326,6 +326,12 @@ export class GrpcConnection implements Connection {
     return stream;
   }
 
+  /**
+   * Closes and cleans up any resources associated with the GrpcConnection.
+   * If a gRPC client has been generated for this connection, the gRPC client
+   * is closed. Failure to call terminate on a GrpcConnection can result
+   * in leaked resources of the gRPC client.
+   */
   terminate(): void {
     if (this.cachedStub) {
       this.cachedStub.close();

packages/firestore/src/remote/connection.ts

@@ -92,6 +92,11 @@ export interface Connection {
    */
   readonly shouldResourcePathBeIncludedInRequest: boolean;
 
+  /**
+   * Closes and cleans up any resources associated with the connection. Actual
+   * resources cleaned are implementation specific. Failure to call `terminate`
+   * on a connection may result in resource leaks.
+   */
   terminate(): void;
 
   // TODO(mcg): subscribe to connection state changes.

packages/firestore/src/remote/rest_connection.ts

@@ -190,6 +190,11 @@ export abstract class RestConnection implements Connection {
     return `${this.baseUrl}/${RPC_URL_VERSION}/${path}:${urlRpcName}`;
   }
 
+  /**
+   * Closes and cleans up any resources associated with the connection. This
+   * implementation is a no-op because there are no resources associated
+   * with the RestConnection that need to be cleaned up.
+   */
   terminate(): void {
     // No-op
   }