File syn_backoff.c

File List > src > syntropic > util > syn_backoff.c

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#include "syn_backoff.h"

#include "syn_assert.h"
#include "syn_random.h"

#include <string.h>

void syn_backoff_init(SYN_Backoff *b, uint32_t min_ms, uint32_t max_ms, uint8_t factor,
                      uint8_t max_attempts)
{
    SYN_ASSERT(b != NULL);
    (void)memset(b, 0, sizeof(*b));
    b->min_ms = min_ms;
    b->max_ms = max_ms;
    b->max_attempts = max_attempts;
    b->factor = (factor < 1) ? 1 : factor;
    syn_backoff_reset(b);
}

void syn_backoff_reset(SYN_Backoff *b)
{
    SYN_ASSERT(b != NULL);
    b->current_ms = b->min_ms;
    b->attempts = 0;
}

uint32_t syn_backoff_next_ms(SYN_Backoff *b)
{
    SYN_ASSERT(b != NULL);

    /* 1. Calculate delay for THIS attempt (including jitter) */
    uint32_t base = b->current_ms;
    uint32_t jitter_max = base / 2;
    uint32_t delay = base;
    if (jitter_max > 0) {
        delay += syn_random_range(0, jitter_max);
    }

    /* 2. Update state for NEXT attempt */
    uint64_t next = (uint64_t)b->current_ms * b->factor;
    if (next > b->max_ms) {
        b->current_ms = b->max_ms;
    } else {
        b->current_ms = (uint32_t)next;
    }
    b->attempts++;

    return delay;
}

bool syn_backoff_exhausted(const SYN_Backoff *b)
{
    SYN_ASSERT(b != NULL);
    return b->attempts >= b->max_attempts;
}