/* (c) 2009 Jerome Loyet */

#include "php.h"
#include "SAPI.h"
#include <stdio.h>
#include <time.h>

#include "fpm_config.h"
#include "fpm_children.h"
#include "fpm_scoreboard.h"
#include "fpm_shm.h"
#include "fpm_sockets.h"
#include "fpm_worker_pool.h"
#include "fpm_clock.h"
#include "zlog.h"

static struct fpm_scoreboard_s *fpm_scoreboard = NULL;
static int fpm_scoreboard_i = -1;
#ifdef HAVE_TIMES
static float fpm_scoreboard_tick;
#endif


int fpm_scoreboard_init_main(void)
{
	struct fpm_worker_pool_s *wp;

#ifdef HAVE_TIMES
#ifdef _SC_CLK_TCK
	fpm_scoreboard_tick = sysconf(_SC_CLK_TCK);
#else /* _SC_CLK_TCK */
#ifdef HZ
	fpm_scoreboard_tick = HZ;
#else /* HZ */
	fpm_scoreboard_tick = 100;
#endif /* HZ */
#endif /* _SC_CLK_TCK */
	zlog(ZLOG_DEBUG, "got clock tick '%.0f'", fpm_scoreboard_tick);
#endif /* HAVE_TIMES */


	for (wp = fpm_worker_all_pools; wp; wp = wp->next) {
		size_t scoreboard_procs_size;
		void *shm_mem;

		if (wp->config->pm_max_children < 1) {
			zlog(ZLOG_ERROR, "[pool %s] Unable to create scoreboard SHM because max_client is not set", wp->config->name);
			return -1;
		}

		if (wp->scoreboard) {
			zlog(ZLOG_ERROR, "[pool %s] Unable to create scoreboard SHM because it already exists", wp->config->name);
			return -1;
		}

		scoreboard_procs_size = sizeof(struct fpm_scoreboard_proc_s) * wp->config->pm_max_children;
		shm_mem = fpm_shm_alloc(sizeof(struct fpm_scoreboard_s) + scoreboard_procs_size);

		if (!shm_mem) {
			return -1;
		}
		wp->scoreboard = shm_mem;
		wp->scoreboard->pm = wp->config->pm;
		wp->scoreboard->nprocs = wp->config->pm_max_children;
		wp->scoreboard->start_epoch = time(NULL);
		strlcpy(wp->scoreboard->pool, wp->config->name, sizeof(wp->scoreboard->pool));

		if (wp->shared) {
			/* shared pool is added after non shared ones so the shared scoreboard is allocated */
			wp->scoreboard->shared = wp->shared->scoreboard;
		}
	}
	return 0;
}

static inline void fpm_scoreboard_readers_decrement(struct fpm_scoreboard_s *scoreboard)
{
	fpm_spinlock(&scoreboard->lock, 1);
	if (scoreboard->reader_count > 0) {
		scoreboard->reader_count -= 1;
	}
#ifdef PHP_FPM_ZLOG_TRACE
	unsigned int current_reader_count = scoreboard->reader_count;
#endif
	fpm_unlock(scoreboard->lock);
#ifdef PHP_FPM_ZLOG_TRACE
	/* this is useful for debugging but currently needs to be hidden as external logger would always log it */
	zlog(ZLOG_DEBUG, "scoreboard: for proc %d reader decremented to value %u", getpid(), current_reader_count);
#endif
}

static struct fpm_scoreboard_s *fpm_scoreboard_get_for_update(struct fpm_scoreboard_s *scoreboard) /* {{{ */
{
	if (!scoreboard) {
		scoreboard = fpm_scoreboard;
	}
	if (!scoreboard) {
		zlog(ZLOG_WARNING, "Unable to update scoreboard: the SHM has not been found");
	}

	return scoreboard;
}
/* }}} */

void fpm_scoreboard_update_begin(struct fpm_scoreboard_s *scoreboard) /* {{{ */
{
	scoreboard = fpm_scoreboard_get_for_update(scoreboard);
	if (!scoreboard) {
		return;
	}

	int retries = 0;
	while (1) {
		fpm_spinlock(&scoreboard->lock, 1);
		if (scoreboard->reader_count == 0) {
			if (!fpm_spinlock_with_max_retries(&scoreboard->writer_active, FPM_SCOREBOARD_SPINLOCK_MAX_RETRIES)) {
				/* in this case the writer might have crashed so just warn and continue as the lock was acquired */
				zlog(ZLOG_WARNING, "scoreboard: writer %d waited too long for another writer to release lock.", getpid());
			}
#ifdef PHP_FPM_ZLOG_TRACE
			else {
				zlog(ZLOG_DEBUG, "scoreboard: writer lock acquired by writer %d", getpid());
			}
#endif
			fpm_unlock(scoreboard->lock);
			break;
		}
		fpm_unlock(scoreboard->lock);

		if (++retries > FPM_SCOREBOARD_SPINLOCK_MAX_RETRIES) {
			/* decrement reader count by 1 (assuming a killed or crashed reader) */
			fpm_scoreboard_readers_decrement(scoreboard);
			zlog(ZLOG_WARNING, "scoreboard: writer detected a potential crashed reader, decrementing reader count.");
			retries = 0;
		}

		sched_yield();
	}
}
/* }}} */

void fpm_scoreboard_update_commit(
		int idle, int active, int lq, int lq_len, int requests, int max_children_reached,
		int slow_rq, size_t memory_peak, int action, struct fpm_scoreboard_s *scoreboard) /* {{{ */
{
	scoreboard = fpm_scoreboard_get_for_update(scoreboard);
	if (!scoreboard) {
		return;
	}

	if (action == FPM_SCOREBOARD_ACTION_SET) {
		if (idle >= 0) {
			scoreboard->idle = idle;
		}
		if (active >= 0) {
			scoreboard->active = active;
		}
		if (lq >= 0) {
			scoreboard->lq = lq;
		}
		if (lq_len >= 0) {
			scoreboard->lq_len = lq_len;
		}
#if HAVE_FPM_LQ /* prevent unnecessary test */
		if (scoreboard->lq > scoreboard->lq_max) {
			scoreboard->lq_max = scoreboard->lq;
		}
#endif
		if (requests >= 0) {
			scoreboard->requests = requests;
		}

		if (max_children_reached >= 0) {
			scoreboard->max_children_reached = max_children_reached;
		}
		if (slow_rq > 0) {
			scoreboard->slow_rq = slow_rq;
		}
	} else {
		if (scoreboard->idle + idle > 0) {
			scoreboard->idle += idle;
		} else {
			scoreboard->idle = 0;
		}

		if (scoreboard->active + active > 0) {
			scoreboard->active += active;
		} else {
			scoreboard->active = 0;
		}

		if (scoreboard->requests + requests > 0) {
			scoreboard->requests += requests;
		} else {
			scoreboard->requests = 0;
		}

		if (scoreboard->max_children_reached + max_children_reached > 0) {
			scoreboard->max_children_reached += max_children_reached;
		} else {
			scoreboard->max_children_reached = 0;
		}

		if (scoreboard->slow_rq + slow_rq > 0) {
			scoreboard->slow_rq += slow_rq;
		} else {
			scoreboard->slow_rq = 0;
		}
	}

	if (scoreboard->active > scoreboard->active_max) {
		scoreboard->active_max = scoreboard->active;
	}
	if (scoreboard->memory_peak < memory_peak) {
		scoreboard->memory_peak = memory_peak;
	}

	fpm_unlock(scoreboard->writer_active);
#ifdef PHP_FPM_ZLOG_TRACE
	zlog(ZLOG_DEBUG, "scoreboard: writer lock released by writer %d", getpid());
#endif
}
/* }}} */


void fpm_scoreboard_update(
		int idle, int active, int lq, int lq_len, int requests, int max_children_reached,
		int slow_rq, size_t memory_peak, int action, struct fpm_scoreboard_s *scoreboard) /* {{{ */
{
	fpm_scoreboard_update_begin(scoreboard);
	fpm_scoreboard_update_commit(
			idle, active, lq, lq_len, requests, max_children_reached, slow_rq, memory_peak, action, scoreboard);
}
/* }}} */

struct fpm_scoreboard_s *fpm_scoreboard_get(void)
{
	return fpm_scoreboard;
}

static inline struct fpm_scoreboard_proc_s *fpm_scoreboard_proc_get_ex(
		struct fpm_scoreboard_s *scoreboard, int child_index, unsigned int nprocs) /* {{{*/
{
	if (!scoreboard) {
		return NULL;
	}

	if (child_index < 0 || (unsigned int)child_index >= nprocs) {
		return NULL;
	}

	return &scoreboard->procs[child_index];
}
/* }}} */

struct fpm_scoreboard_proc_s *fpm_scoreboard_proc_get(
		struct fpm_scoreboard_s *scoreboard, int child_index) /* {{{*/
{
	if (!scoreboard) {
		scoreboard = fpm_scoreboard;
	}

	if (child_index < 0) {
		child_index = fpm_scoreboard_i;
	}

	return fpm_scoreboard_proc_get_ex(scoreboard, child_index, scoreboard->nprocs);
}
/* }}} */

struct fpm_scoreboard_proc_s *fpm_scoreboard_proc_get_from_child(struct fpm_child_s *child) /* {{{*/
{
	struct fpm_worker_pool_s *wp = child->wp;
	unsigned int nprocs = wp->config->pm_max_children;
	struct fpm_scoreboard_s *scoreboard = wp->scoreboard;
	int child_index = child->scoreboard_i;

	return fpm_scoreboard_proc_get_ex(scoreboard, child_index, nprocs);
}
/* }}} */


struct fpm_scoreboard_s *fpm_scoreboard_acquire(struct fpm_scoreboard_s *scoreboard, int nohang) /* {{{ */
{
	struct fpm_scoreboard_s *s = scoreboard ? scoreboard : fpm_scoreboard;
	if (!s) {
		return NULL;
	}

	int retries = 0;
	while (1) {
		/* increment reader if no writer active */
		fpm_spinlock(&s->lock, 1);
		if (!s->writer_active) {
			s->reader_count += 1;
#ifdef PHP_FPM_ZLOG_TRACE
			unsigned int current_reader_count = s->reader_count;
#endif
			fpm_unlock(s->lock);
#ifdef PHP_FPM_ZLOG_TRACE
			zlog(ZLOG_DEBUG, "scoreboard: for proc %d reader incremented to value %u", getpid(), current_reader_count);
#endif
			break;
		}
		fpm_unlock(s->lock);

		sched_yield();

        if (++retries > FPM_SCOREBOARD_SPINLOCK_MAX_RETRIES) {
            zlog(ZLOG_WARNING, "scoreboard: reader waited too long for writer to release lock.");
			fpm_scoreboard_readers_decrement(s);
			return NULL;
        }
	}

	return s;
}
/* }}} */

void fpm_scoreboard_release(struct fpm_scoreboard_s *scoreboard) {
	if (!scoreboard) {
		return;
	}

	fpm_scoreboard_readers_decrement(scoreboard);
}

struct fpm_scoreboard_s *fpm_scoreboard_copy(struct fpm_scoreboard_s *scoreboard, int copy_procs)
{
	struct fpm_scoreboard_s *scoreboard_copy;
	struct fpm_scoreboard_proc_s *scoreboard_proc_p;
	size_t scoreboard_size, scoreboard_nprocs_size;
	int i;
	void *mem;

	if (!scoreboard) {
		scoreboard = fpm_scoreboard_get();
	}

	if (copy_procs) {
		scoreboard_size = sizeof(struct fpm_scoreboard_s);
		scoreboard_nprocs_size = sizeof(struct fpm_scoreboard_proc_s) * scoreboard->nprocs;

		mem = malloc(scoreboard_size + scoreboard_nprocs_size);
	} else {
		mem = malloc(sizeof(struct fpm_scoreboard_s));
	}

	if (!mem) {
		zlog(ZLOG_ERROR, "scoreboard: failed to allocate memory for copy");
		return NULL;
	}

	scoreboard_copy = mem;

	scoreboard = fpm_scoreboard_acquire(scoreboard, FPM_SCOREBOARD_LOCK_NOHANG);
	if (!scoreboard) {
		free(mem);
		zlog(ZLOG_ERROR, "scoreboard: failed to lock (already locked)");
		return NULL;
	}

	*scoreboard_copy = *scoreboard;

	if (copy_procs) {
		mem += scoreboard_size;

		for (i = 0; i < scoreboard->nprocs; i++, mem += sizeof(struct fpm_scoreboard_proc_s)) {
			scoreboard_proc_p = fpm_scoreboard_proc_acquire(scoreboard, i, FPM_SCOREBOARD_LOCK_HANG);
			scoreboard_copy->procs[i] = *scoreboard_proc_p;
			fpm_scoreboard_proc_release(scoreboard_proc_p);
		}
	}

	fpm_scoreboard_release(scoreboard);

	return scoreboard_copy;
}

void fpm_scoreboard_free_copy(struct fpm_scoreboard_s *scoreboard)
{
	free(scoreboard);
}

struct fpm_scoreboard_proc_s *fpm_scoreboard_proc_acquire(struct fpm_scoreboard_s *scoreboard, int child_index, int nohang) /* {{{ */
{
	struct fpm_scoreboard_proc_s *proc;

	proc = fpm_scoreboard_proc_get(scoreboard, child_index);
	if (!proc) {
		return NULL;
	}

	if (!fpm_spinlock(&proc->lock, nohang)) {
		return NULL;
	}

	return proc;
}
/* }}} */

void fpm_scoreboard_proc_release(struct fpm_scoreboard_proc_s *proc) /* {{{ */
{
	if (!proc) {
		return;
	}

	proc->lock = 0;
}

void fpm_scoreboard_free(struct fpm_worker_pool_s *wp) /* {{{ */
{
	size_t scoreboard_procs_size;
	struct fpm_scoreboard_s *scoreboard = wp->scoreboard;

	if (!scoreboard) {
		zlog(ZLOG_ERROR, "**scoreboard is NULL");
		return;
	}

	scoreboard_procs_size = sizeof(struct fpm_scoreboard_proc_s) * wp->config->pm_max_children;

	fpm_shm_free(scoreboard, sizeof(struct fpm_scoreboard_s) + scoreboard_procs_size);
}
/* }}} */

void fpm_scoreboard_child_use(struct fpm_child_s *child, pid_t pid) /* {{{ */
{
	struct fpm_scoreboard_proc_s *proc;
	fpm_scoreboard = child->wp->scoreboard;
	fpm_scoreboard_i = child->scoreboard_i;
	proc = fpm_scoreboard_proc_get_from_child(child);
	if (!proc) {
		return;
	}
	proc->pid = pid;
	proc->start_epoch = time(NULL);
}
/* }}} */

void fpm_scoreboard_proc_free(struct fpm_child_s *child) /* {{{ */
{
	struct fpm_worker_pool_s *wp = child->wp;
	struct fpm_scoreboard_s *scoreboard = wp->scoreboard;
	int child_index = child->scoreboard_i;

	if (!scoreboard) {
		return;
	}

	if (child_index < 0 || child_index >= wp->config->pm_max_children) {
		return;
	}

	if (scoreboard->procs[child_index].used > 0) {
		memset(&scoreboard->procs[child_index], 0, sizeof(struct fpm_scoreboard_proc_s));
	}

	/* set this slot as free to avoid search on next alloc */
	scoreboard->free_proc = child_index;
}
/* }}} */

int fpm_scoreboard_proc_alloc(struct fpm_child_s *child) /* {{{ */
{
	int i = -1;
	struct fpm_worker_pool_s *wp = child->wp;
	struct fpm_scoreboard_s *scoreboard = wp->scoreboard;
	int nprocs = wp->config->pm_max_children;

	if (!scoreboard) {
		return -1;
	}

	/* first try the slot which is supposed to be free */
	if (scoreboard->free_proc >= 0 && scoreboard->free_proc < nprocs) {
		if (!scoreboard->procs[scoreboard->free_proc].used) {
			i = scoreboard->free_proc;
		}
	}

	if (i < 0) { /* the supposed free slot is not, let's search for a free slot */
		zlog(ZLOG_DEBUG, "[pool %s] the proc->free_slot was not free. Let's search", scoreboard->pool);
		for (i = 0; i < nprocs; i++) {
			if (!scoreboard->procs[i].used) { /* found */
				break;
			}
		}
	}

	/* no free slot */
	if (i < 0 || i >= nprocs) {
		zlog(ZLOG_ERROR, "[pool %s] no free scoreboard slot", scoreboard->pool);
		return -1;
	}

	scoreboard->procs[i].used = 1;
	child->scoreboard_i = i;

	/* supposed next slot is free */
	if (i + 1 >= nprocs) {
		scoreboard->free_proc = 0;
	} else {
		scoreboard->free_proc = i + 1;
	}

	return 0;
}
/* }}} */

#ifdef HAVE_TIMES
float fpm_scoreboard_get_tick(void)
{
	return fpm_scoreboard_tick;
}
#endif