Retry State

A retry state machine can alternate between ready and waiting, then stop after too many failures.

retry_state.c

#include <stdio.h>

enum RetryState {
    RETRY_READY,
    RETRY_WAITING,
    RETRY_STOPPED
};

enum RetryState nextRetry(enum RetryState state, int failures) {
    if (failures >= 3) {
        return RETRY_STOPPED;
    }
    if (state == RETRY_READY) {
        return RETRY_WAITING;
    }
    return RETRY_READY;
}

int main(void) {
    int failures = ;
    enum RetryState state = RETRY_READY;

    state = nextRetry(state, failures);
    state = nextRetry(state, failures + 1);

    printf("failures=%d state=%d\n", failures, state);
    return 0;
}

#include <stdio.h>

enum RetryState {
    RETRY_READY,
    RETRY_WAITING,
    RETRY_STOPPED
};

enum RetryState nextRetry(enum RetryState state, int failures) {
    if (failures >= 3) {
        return RETRY_STOPPED;
    }
    if (state == RETRY_READY) {
        return RETRY_WAITING;
    }
    return RETRY_READY;
}

int main(void) {
    int failures = ;
    enum RetryState state = RETRY_READY;

    state = nextRetry(state, failures);
    state = nextRetry(state, failures + 1);

    printf("failures=%d state=%d\n", failures, state);
    return 0;
}

#include <stdio.h>

enum RetryState {
    RETRY_READY,
    RETRY_WAITING,
    RETRY_STOPPED
};

enum RetryState nextRetry(enum RetryState state, int failures) {
    if (failures >= 3) {
        return RETRY_STOPPED;
    }
    if (state == RETRY_READY) {
        return RETRY_WAITING;
    }
    return RETRY_READY;
}

int main(void) {
    int failures = ;
    enum RetryState state = RETRY_READY;

    state = nextRetry(state, failures);
    state = nextRetry(state, failures + 1);

    printf("failures=%d state=%d\n", failures, state);
    return 0;
}

guard A guard condition can stop the machine before normal alternation continues.

retry The state tells the caller whether to try now, wait, or stop.