Function overMaxmemoryAfterAlloc

src/evict.cpp:538–548

Return 1 if used memory is more than maxmemory after allocating more memory, * return 0 if not. Redis may reject user's requests or evict some keys if used * memory exceeds maxmemory, especially, when we allocate huge memory at once. */

 * return 0 if not. Redis may reject user's requests or evict some keys if used
 * memory exceeds maxmemory, especially, when we allocate huge memory at once. */
int overMaxmemoryAfterAlloc(size_t moremem) {
    if (!g_pserver->maxmemory) return  0; /* No limit. */

    /* Check quickly. */
    size_t mem_used = zmalloc_used_memory();
    if (mem_used + moremem <= g_pserver->maxmemory) return 0;

    size_t overhead = freeMemoryGetNotCountedMemory();
    mem_used = (mem_used > overhead) ? mem_used - overhead : 0;
    return mem_used + moremem > g_pserver->maxmemory;
}

/* The evictionTimeProc is started when "maxmemory" has been breached and
 * could not immediately be resolved.  This will spin the event loop with short