Stuck in stage 19

Challenges
1

I’m stuck on Stage stage 19.

I’ve tried the below code.

Here are my logs:

remote: [tester::#YG4] Running tests for Stage #YG4 (Replication - Command Processing)
remote: [tester::#YG4] Master is running on port 6379
remote: [tester::#YG4] $ ./spawn_redis_server.sh --port 6380 --replicaof "localhost 6379"
remote: [your_program] Logs from your program will appear here!
remote: [tester::#YG4] master: Waiting for replica to initiate handshake with "PING" command
remote: [tester::#YG4] master: Received bytes: "*1\r\n$4\r\nPING\r\n"
remote: [tester::#YG4] master: Received RESP value: ["PING"]
remote: [tester::#YG4] Received ["PING"]
remote: [tester::#YG4] master: Sent "PONG"
remote: [tester::#YG4] master: Sent bytes: "+PONG\r\n"
remote: [tester::#YG4] master: Waiting for replica to send "REPLCONF listening-port 6380" command
remote: [your_program] +PONG
remote: [your_program] 
remote: [tester::#YG4] master: Received bytes: "*3\r\n$8\r\nREPLCONF\r\n$14\r\nlistening-port\r\n$4\r\n6380\r\n"
remote: [tester::#YG4] master: Received RESP value: ["REPLCONF", "listening-port", "6380"]
remote: [tester::#YG4] Received ["REPLCONF", "listening-port", "6380"]
remote: [tester::#YG4] master: Sent "OK"
remote: [tester::#YG4] master: Sent bytes: "+OK\r\n"
remote: [tester::#YG4] master: Waiting for replica to send "REPLCONF capa" command
remote: [your_program] +OK
remote: [your_program] 
remote: [tester::#YG4] master: Received bytes: "*3\r\n$8\r\nREPLCONF\r\n$4\r\ncapa\r\n$6\r\npsync2\r\n"
remote: [tester::#YG4] master: Received RESP value: ["REPLCONF", "capa", "psync2"]
remote: [tester::#YG4] Received ["REPLCONF", "capa", "psync2"]
remote: [tester::#YG4] master: Sent "OK"
remote: [tester::#YG4] master: Sent bytes: "+OK\r\n"
remote: [tester::#YG4] master: Waiting for replica to send "PSYNC" command
remote: [your_program] +OK
remote: [your_program] 
remote: [tester::#YG4] master: Received bytes: "*3\r\n$5\r\nPSYNC\r\n$1\r\n?\r\n$2\r\n-1\r\n"
remote: [tester::#YG4] master: Received RESP value: ["PSYNC", "?", "-1"]
remote: [tester::#YG4] Received ["PSYNC", "?", "-1"]
remote: [tester::#YG4] master: Sent "FULLRESYNC 75cd7bc10c49047e0d163660f3b90625b1af31dc 0"
remote: [tester::#YG4] master: Sent bytes: "+FULLRESYNC 75cd7bc10c49047e0d163660f3b90625b1af31dc 0\r\n"
remote: [tester::#YG4] Sending RDB file...
remote: [tester::#YG4] master: Sent bytes: "$88\r\nREDIS0011\xfa\tredis-ver\x057.2.0\xfa\nredis-bits\xc0@\xfa\x05ctime\xc2m\b\xbce\xfa\bused-mem°\xc4\x10\x00\xfa\baof-base\xc0\x00\xff\xf0n;\xfe\xc0\xffZ\xa2"
remote: [tester::#YG4] Sent RDB file.
remote: [your_program] +FULLRESYNC 75cd7bc10c49047e0d163660f3b90625b1af31dc 0
remote: [your_program] 
remote: [tester::#YG4] master: $ redis-cli SET foo 123
remote: [tester::#YG4] master: Sent bytes: "*3\r\n$3\r\nSET\r\n$3\r\nfoo\r\n$3\r\n123\r\n"
remote: [tester::#YG4] master: $ redis-cli SET bar 456
remote: [tester::#YG4] master: Sent bytes: "*3\r\n$3\r\nSET\r\n$3\r\nbar\r\n$3\r\n456\r\n"
remote: [tester::#YG4] master: $ redis-cli SET baz 789
remote: [tester::#YG4] master: Sent bytes: "*3\r\n$3\r\nSET\r\n$3\r\nbaz\r\n$3\r\n789\r\n"
remote: [tester::#YG4] Getting key foo
remote: [tester::#YG4] client: $ redis-cli GET foo
remote: [tester::#YG4] client: Sent bytes: "*2\r\n$3\r\nGET\r\n$3\r\nfoo\r\n"
remote: [your_program] REPLICA --> {}
remote: [tester::#YG4] client: Received bytes: "$-1\r\n"
remote: [tester::#YG4] client: Received RESP value: NIL
remote: [tester::#YG4] Retrying... (1/5 attempts)
remote: [tester::#YG4] client: $ redis-cli GET foo
remote: [tester::#YG4] client: Sent bytes: "*2\r\n$3\r\nGET\r\n$3\r\nfoo\r\n"
remote: [your_program] REPLICA --> {}
remote: [tester::#YG4] client: Received bytes: "$-1\r\n"
remote: [tester::#YG4] client: Received RESP value: NIL
remote: [tester::#YG4] Retrying... (2/5 attempts)
remote: [tester::#YG4] client: $ redis-cli GET foo
remote: [tester::#YG4] client: Sent bytes: "*2\r\n$3\r\nGET\r\n$3\r\nfoo\r\n"
remote: [your_program] REPLICA --> {}
remote: [tester::#YG4] client: Received bytes: "$-1\r\n"
remote: [tester::#YG4] client: Received RESP value: NIL
remote: [tester::#YG4] Retrying... (3/5 attempts)
remote: [tester::#YG4] client: $ redis-cli GET foo
remote: [tester::#YG4] client: Sent bytes: "*2\r\n$3\r\nGET\r\n$3\r\nfoo\r\n"
remote: [tester::#YG4] client: Received bytes: "$-1\r\n"
remote: [tester::#YG4] client: Received RESP value: NIL
remote: [your_program] REPLICA --> {}
remote: [tester::#YG4] Retrying... (4/5 attempts)
remote: [tester::#YG4] client: $ redis-cli GET foo
remote: [tester::#YG4] client: Sent bytes: "*2\r\n$3\r\nGET\r\n$3\r\nfoo\r\n"
remote: [tester::#YG4] client: Received bytes: "$-1\r\n"
remote: [tester::#YG4] client: Received RESP value: NIL
remote: [your_program] REPLICA --> {}
remote: [tester::#YG4] Retrying... (5/5 attempts)
remote: [tester::#YG4] client: $ redis-cli GET foo
remote: [tester::#YG4] client: Sent bytes: "*2\r\n$3\r\nGET\r\n$3\r\nfoo\r\n"
remote: [your_program] REPLICA --> {}
remote: [tester::#YG4] client: Received bytes: "$-1\r\n"
remote: [tester::#YG4] client: Received RESP value: NIL
remote: [tester::#YG4] Expected simple string or bulk string, got NIL
remote: [tester::#YG4] Test failed
remote: [tester::#YG4] Terminating program
remote: [tester::#YG4] Program terminated successfully

And here’s a snippet of my code:

public void handleRequest(Socket clientSocket) {
        try {
            while (clientSocket.isConnected()) {
                byte[] input = new byte[1024];
                int bytesRead = clientSocket.getInputStream().read(input);
                String rawRequest = new String(input, 0, bytesRead);
                String request = rawRequest.trim();
                String[] parts = request.split("\r\n");
                if (parts.length >= 2) {
                    if (parts[2].equalsIgnoreCase("SET")) {
                        String key = parts[4];
                        String value = parts[6];
                        long timeout = parts.length == 11 ? Long.parseLong(parts[10]) : 0;
                        Data data = new Data(value, timeout);
                        storage.put(key, data);
                        if (Role.REPLICA.name().equals(role.name())) {
                            System.out.println(role + " --> " + storage);
                        }
                        if (Role.MASTER.name().equals(role.name())) {
                            String response = "OK";
                            clientSocket.getOutputStream().write(("$" + response.length() + "\r\n" + response + "\r\n")
                                    .getBytes());
                            sendToReplicas(rawRequest);
                        }
                    } else if (parts[2].equalsIgnoreCase("GET")) {
                        Object rawData = storage.get(parts[4]);
                        String value = null;
                        if (Objects.nonNull(rawData)) {
                            Data data = (Data) rawData;
                            if (data.expiry > 0 && data.expiry < System.currentTimeMillis()) {
                                storage.remove(parts[4]);
                            } else {
                                value = (String) data.value;
                            }
                        }
                        if (Role.REPLICA.name().equals(role.name())) {
                            System.out.println(role + " --> " + storage);
                        }
                        if (Objects.nonNull(value)) {
                            clientSocket.getOutputStream().write(
                                    ("$" + value.length() + "\r\n" + value + "\r\n").getBytes());
                        } else {
                            clientSocket.getOutputStream().write(
                                    ("$-1\r\n").getBytes());
                        }
                    } else if (parts[2].equalsIgnoreCase("INFO")) {
                        StringBuilder builder = new StringBuilder();
                        infoMap.forEach((key, value) -> builder.append(key).append(":").append(value));
                        String value = builder.toString();
                        clientSocket.getOutputStream().write(
                                ("$" + value.length() + "\r\n" + value + "\r\n").getBytes());
                    } else if (parts[2].equalsIgnoreCase("REPLCONF") && Role.MASTER.name().equals(role.name())) {
                        String data = "OK";
                        clientSocket.getOutputStream().write(
                                ("$" + data.length() + "\r\n" + data + "\r\n").getBytes());
                    } else if (parts[2].equalsIgnoreCase("PSYNC") && Role.MASTER.name().equals(role.name())) {
                        String replID = REPL_ID + UUID.randomUUID().toString().substring(25);
                        String data = String.format("+FULLRESYNC %s %d%s", replID, OFFSET, "\r\n");
                        clientSocket.getOutputStream().write(data.getBytes());
                        clientSocket.getOutputStream().flush();
                        String fileContents = "UkVESVMwMDEx+glyZWRpcy12ZXIFNy4yLjD6CnJlZGlzLWJpdHPAQPoFY3RpbWXCbQi8ZfoIdXNlZC1tZW3CsMQQAPoIYW9mLWJhc2XAAP/wbjv+wP9aog==";
                        byte[] bytes = Base64.getDecoder().decode(fileContents);
                        clientSocket.getOutputStream().write(("$" + bytes.length + "\r\n").getBytes());
                        clientSocket.getOutputStream().flush();
                        clientSocket.getOutputStream().write(bytes);
                        clientSocket.getOutputStream().flush();
                        replicaMap.put(replID, clientSocket);
                    } else if (parts[2].equalsIgnoreCase("ECHO")) {
                        String data = parts[4];
                        clientSocket.getOutputStream().write(
                                ("$" + data.length() + "\r\n" + data + "\r\n").getBytes());
                    } else if (parts[2].equalsIgnoreCase("PING")) {
                        System.out.println("Sending Pong....");
                        clientSocket.getOutputStream().write("+PONG\r\n".getBytes());
                    } else {
                        clientSocket.getOutputStream().write(
                                "-ERR invalid request\r\n".getBytes());
                    }
                } else {
                    clientSocket.getOutputStream().write(
                            "-ERR invalid request\r\n".getBytes());
                }
            }
        } catch (IOException e) {
            System.err.println("Error handling client: " + e.getMessage());
        }
    }

    private void sendToReplicas(String request) {
        replicaMap.forEach((replicaId, socket) -> {
            CompletableFuture.runAsync(() -> {
                try {
                    System.out.println("Sending to replicas");
                    socket.getOutputStream().write(request.getBytes(StandardCharsets.UTF_8));
                    socket.getOutputStream().flush();
                    String response = ReplicaRequestHandler.getResponse(socket);
                    System.out.println(response);
                } catch (IOException e) {
                    e.printStackTrace();
                }
            });
        });
    }
2

The master may send all the set commands to the replica together in a resp array.
Your code handles individual set commands correctly but you need to write a parser for parsing the resp array and then loop over the individual commands to resolve your error.

Hope this helps!!

3

Thanks for the reply. Tried having the parser for resp array, it didn’t help either…

public void handleRequest(Socket clientSocket) {
        try {
            while (clientSocket.isConnected()) {
                String[] rawRequests = getRawRequests(clientSocket);
                for (String rawRequest : rawRequests) {
                    String request = rawRequest.trim();
                    String[] parts = request.split("\r\n");
                    if (parts.length >= 2) {
                        if (parts[2].equalsIgnoreCase("SET")) {
                            String key = parts[4];
                            String value = parts[6];
                            long timeout = parts.length == 11 ? Long.parseLong(parts[10]) : 0;
                            Data data = new Data(value, timeout);
                            storage.put(key, data);
                            if (Role.REPLICA.name().equals(role.name())) {
                                System.out.println(role + " --> " + storage);
                            }
                            if (Role.MASTER.name().equals(role.name())) {
                                String response = "OK";
                                clientSocket.getOutputStream().write(("$" + response.length() + "\r\n" + response + "\r\n")
                                        .getBytes());
                                sendToReplicas(rawRequest);
                            }
                        } else if (parts[2].equalsIgnoreCase("GET")) {
                            Object rawData = storage.get(parts[4]);
                            String value = null;
                            if (Objects.nonNull(rawData)) {
                                Data data = (Data) rawData;
                                if (data.expiry > 0 && data.expiry < System.currentTimeMillis()) {
                                    storage.remove(parts[4]);
                                } else {
                                    value = (String) data.value;
                                }
                            }
                            if (Role.REPLICA.name().equals(role.name())) {
                                System.out.println(role + " --> " + storage);
                            }
                            if (Objects.nonNull(value)) {
                                clientSocket.getOutputStream().write(
                                        ("$" + value.length() + "\r\n" + value + "\r\n").getBytes());
                            } else {
                                clientSocket.getOutputStream().write(
                                        ("$-1\r\n").getBytes());
                            }
                        } else if (parts[2].equalsIgnoreCase("INFO")) {
                            StringBuilder builder = new StringBuilder();
                            infoMap.forEach((key, value) -> builder.append(key).append(":").append(value));
                            String value = builder.toString();
                            clientSocket.getOutputStream().write(
                                    ("$" + value.length() + "\r\n" + value + "\r\n").getBytes());
                        } else if (parts[2].equalsIgnoreCase("REPLCONF") && Role.MASTER.name().equals(role.name())) {
                            String data = "OK";
                            clientSocket.getOutputStream().write(
                                    ("$" + data.length() + "\r\n" + data + "\r\n").getBytes());
                        } else if (parts[2].equalsIgnoreCase("PSYNC") && Role.MASTER.name().equals(role.name())) {
                            String replID = REPL_ID + UUID.randomUUID().toString().substring(25);
                            String data = String.format("+FULLRESYNC %s %d%s", replID, OFFSET, "\r\n");
                            clientSocket.getOutputStream().write(data.getBytes());
                            clientSocket.getOutputStream().flush();
                            String fileContents = "UkVESVMwMDEx+glyZWRpcy12ZXIFNy4yLjD6CnJlZGlzLWJpdHPAQPoFY3RpbWXCbQi8ZfoIdXNlZC1tZW3CsMQQAPoIYW9mLWJhc2XAAP/wbjv+wP9aog==";
                            byte[] bytes = Base64.getDecoder().decode(fileContents);
                            clientSocket.getOutputStream().write(("$" + bytes.length + "\r\n").getBytes());
                            clientSocket.getOutputStream().flush();
                            clientSocket.getOutputStream().write(bytes);
                            clientSocket.getOutputStream().flush();
                            replicaMap.put(replID, clientSocket);
                        } else if (parts[2].equalsIgnoreCase("ECHO")) {
                            String data = parts[4];
                            clientSocket.getOutputStream().write(
                                    ("$" + data.length() + "\r\n" + data + "\r\n").getBytes());
                        } else if (parts[2].equalsIgnoreCase("PING")) {
                            System.out.println("Sending Pong....");
                            clientSocket.getOutputStream().write("+PONG\r\n".getBytes());
                        } else {
                            clientSocket.getOutputStream().write(
                                    "-ERR invalid request\r\n".getBytes());
                        }
                    } else {
                        clientSocket.getOutputStream().write(
                                "-ERR invalid request\r\n".getBytes());
                    }
                }
            }
        } catch (IOException e) {
            System.err.println("Error handling client: " + e.getMessage());
        }
    }

    private String[] getRawRequests(Socket clientSocket) throws IOException {
        byte[] input = new byte[4024];
        int bytesRead = clientSocket.getInputStream().read(input);
        String rawRequest = new String(input, 0, bytesRead);
        String[] resps = rawRequest.split("\\*");
        String[] rawRequests = new String[resps.length];
        int i = 0;
        for (String resp : resps) {
            if (!resp.equals("")) {
                rawRequests[i] = "*" + resp;
                i++;
            }
        }
        return rawRequests;
    }```


log

remote: [tester::#YG4] Running tests for Stage #YG4 (Replication - Command Processing)
remote: [tester::#YG4] Master is running on port 6379
remote: [tester::#YG4] $ ./spawn_redis_server.sh --port 6380 --replicaof “localhost 6379”
remote: [your_program] Logs from your program will appear here!
remote: [tester::#YG4] master: Waiting for replica to initiate handshake with “PING” command
remote: [tester::#YG4] master: Received bytes: “*1\r\n$4\r\nPING\r\n”
remote: [tester::#YG4] master: Received RESP value: [“PING”]
remote: [tester::#YG4] Received [“PING”]
remote: [tester::#YG4] master: Sent “PONG”
remote: [tester::#YG4] master: Sent bytes: “+PONG\r\n”
remote: [tester::#YG4] master: Waiting for replica to send “REPLCONF listening-port 6380” command
remote: [your_program] +PONG
remote: [your_program]
remote: [tester::#YG4] master: Received bytes: “*3\r\n$8\r\nREPLCONF\r\n$14\r\nlistening-port\r\n$4\r\n6380\r\n”
remote: [tester::#YG4] master: Received RESP value: [“REPLCONF”, “listening-port”, “6380”]
remote: [tester::#YG4] Received [“REPLCONF”, “listening-port”, “6380”]
remote: [tester::#YG4] master: Sent “OK”
remote: [tester::#YG4] master: Sent bytes: “+OK\r\n”
remote: [tester::#YG4] master: Waiting for replica to send “REPLCONF capa” command
remote: [your_program] +OK
remote: [your_program]
remote: [tester::#YG4] master: Received bytes: “*3\r\n$8\r\nREPLCONF\r\n$4\r\ncapa\r\n$6\r\npsync2\r\n”
remote: [tester::#YG4] master: Received RESP value: [“REPLCONF”, “capa”, “psync2”]
remote: [tester::#YG4] Received [“REPLCONF”, “capa”, “psync2”]
remote: [tester::#YG4] master: Sent “OK”
remote: [tester::#YG4] master: Sent bytes: “+OK\r\n”
remote: [tester::#YG4] master: Waiting for replica to send “PSYNC” command
remote: [your_program] +OK
remote: [your_program]
remote: [tester::#YG4] master: Received bytes: “*3\r\n$5\r\nPSYNC\r\n$1\r\n?\r\n$2\r\n-1\r\n”
remote: [tester::#YG4] master: Received RESP value: [“PSYNC”, “?”, “-1”]
remote: [tester::#YG4] Received [“PSYNC”, “?”, “-1”]
remote: [tester::#YG4] master: Sent “FULLRESYNC 75cd7bc10c49047e0d163660f3b90625b1af31dc 0”
remote: [tester::#YG4] master: Sent bytes: “+FULLRESYNC 75cd7bc10c49047e0d163660f3b90625b1af31dc 0\r\n”
remote: [tester::#YG4] Sending RDB file…
remote: [tester::#YG4] master: Sent bytes: “$88\r\nREDIS0011\xfa\tredis-ver\x057.2.0\xfa\nredis-bits\xc0@\xfa\x05ctime\xc2m\b\xbce\xfa\bused-mem°\xc4\x10\x00\xfa\baof-base\xc0\x00\xff\xf0n;\xfe\xc0\xffZ\xa2”
remote: [tester::#YG4] Sent RDB file.
remote: [your_program] +FULLRESYNC 75cd7bc10c49047e0d163660f3b90625b1af31dc 0
remote: [your_program] $88
remote: [your_program] REDIS0011� redis-ver7.2.0�
remote: [your_program] redis-bits�@�ctime��eused-mem°�[tester::#YG4] master: $ redis-cli SET foo 123
remote: [tester::#YG4] master: Sent bytes: “*3\r\n$3\r\nSET\r\n$3\r\nfoo\r\n$3\r\n123\r\n”
remote: [tester::#YG4] master: $ redis-cli SET bar 456
remote: [tester::#YG4] master: Sent bytes: “*3\r\n$3\r\nSET\r\n$3\r\nbar\r\n$3\r\n456\r\n”
remote: [tester::#YG4] master: $ redis-cli SET baz 789
remote: [tester::#YG4] master: Sent bytes: “*3\r\n$3\r\nSET\r\n$3\r\nbaz\r\n$3\r\n789\r\n”
remote: [tester::#YG4] Getting key foo
remote: [tester::#YG4] client: $ redis-cli GET foo
remote: [tester::#YG4] client: Sent bytes: “*2\r\n$3\r\nGET\r\n$3\r\nfoo\r\n”
remote: [your_program] REPLICA → {}
remote: [tester::#YG4] client: Received bytes: “$-1\r\n”
remote: [tester::#YG4] client: Received RESP value: NIL
remote: [tester::#YG4] Retrying… (1/5 attempts)
remote: [tester::#YG4] client: $ redis-cli GET foo
remote: [tester::#YG4] client: Sent bytes: “*2\r\n$3\r\nGET\r\n$3\r\nfoo\r\n”
remote: [tester::#YG4] Received: “” (no content received)
remote: [tester::#YG4] ^ error
remote: [tester::#YG4] Error: Expected start of a new RESP2 value (either +, -, :, $ or *)
remote: [tester::#YG4] Test failed
remote: [tester::#YG4] Terminating program
remote: [tester::#YG4] Program terminated successfully

4

@Roopam-91 could you try adding logs around where you’re receiving bytes? The tester mentions sending bytes but I can’t tell if your program parsed those commands correctly or not.

5

Marking as closed for now, please let us know if you still need help!

6

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