io/optimizations: Add checker for async-server

Added a checker for async-server.
Added `make check` rule to the Makefile.
Updated README.md with checker instructions.
Modified the `test-file` size that is being sent from
1GB to 100MB, so the checker can run in a shorter time.

Signed-off-by: Rares Balcan <[email protected]>

Author: raress04

chapters/io/optimizations/drills/tasks/async-server/README.md

@@ -15,7 +15,7 @@ After uploading the file, the clients close the connection.
    If successful, the clients should print the upload progress.
 
    To run the checker, run `make check` from the `support` file. You may have to wait a little bit for the checker to be finish its execution.
-   In case of the checker failing, check out client and server output in the `client_output.log`, `server_output.log` in the  `support` file. 
+   In case of the checker failing, check out client and server output in the `client_output.log`, `server_output.log` in the `support` file.
 
 1. There is a problem with our current implementation.
    Try to start two clients at the same time - the first one will start uploading, and the second one will block at `connect()`.

chapters/io/optimizations/drills/tasks/async-server/solution/Makefile

@@ -42,5 +42,5 @@ check:
 	cd ../tests && \
 	chmod +x check_server.sh && \
 	./check_server.sh
-	
+
 .PHONY: all clean

chapters/io/optimizations/drills/tasks/async-server/tests/check_server.sh

@@ -1,4 +1,5 @@
 #!/bin/bash
+# SPDX-License-Identifier: BSD-3-Clause
 
 TEST_FILE="../support/test-file.txt"
 if [ ! -f "$TEST_FILE" ]; then
@@ -11,7 +12,6 @@ SOLUTION_DIR="../solution"
 PORT=5000
 
 SERVER_BIN="$SUPPORT_DIR/server"
-CLIENT_BIN="$SOLUTION_DIR/client"
 SERVER_LOG="$SUPPORT_DIR/server_output.log"
 CLIENT_LOG="$SUPPORT_DIR/client_output.log"
 REF_CONFIRMATION="Received 100MB file from"
@@ -25,7 +25,7 @@ rm -f "$SERVER_LOG" "$CLIENT_LOG"
 PID_LIST=$(lsof -ti tcp:$PORT)
 if [ -n "$PID_LIST" ]; then
     echo "Killing previous server processes on port $PORT: $PID_LIST"
-    kill -9 $PID_LIST
+    kill -9 "$PID_LIST"
     sleep 1
 fi