/*
   * Resizable, Scalable, Concurrent Hash Table
   *

   * Copyright (c) 2014-2015 Thomas Graf <tgraf@suug.ch>

   * Copyright (c) 2008-2014 Patrick McHardy <kaber@trash.net>
   *

   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   */
  
  /**************************************************************************
   * Self Test
   **************************************************************************/
  
  #include <linux/init.h>
  #include <linux/jhash.h>
  #include <linux/kernel.h>

  #include <linux/kthread.h>

  #include <linux/module.h>
  #include <linux/rcupdate.h>
  #include <linux/rhashtable.h>

  #include <linux/semaphore.h>

  #include <linux/slab.h>

  #include <linux/sched.h>

  #include <linux/vmalloc.h>

  #define MAX_ENTRIES	1000000

  #define TEST_INSERT_FAIL INT_MAX

  
  static int entries = 50000;
  module_param(entries, int, 0);
  MODULE_PARM_DESC(entries, "Number of entries to add (default: 50000)");
  
  static int runs = 4;
  module_param(runs, int, 0);
  MODULE_PARM_DESC(runs, "Number of test runs per variant (default: 4)");

  static int max_size = 0;

  module_param(max_size, int, 0);

  MODULE_PARM_DESC(max_size, "Maximum table size (default: calculated)");

  
  static bool shrinking = false;
  module_param(shrinking, bool, 0);
  MODULE_PARM_DESC(shrinking, "Enable automatic shrinking (default: off)");
  
  static int size = 8;
  module_param(size, int, 0);
  MODULE_PARM_DESC(size, "Initial size hint of table (default: 8)");

  static int tcount = 10;
  module_param(tcount, int, 0);
  MODULE_PARM_DESC(tcount, "Number of threads to spawn (default: 10)");

  static bool enomem_retry = false;
  module_param(enomem_retry, bool, 0);
  MODULE_PARM_DESC(enomem_retry, "Retry insert even if -ENOMEM was returned (default: off)");

  struct test_obj {

  	int			value;
  	struct rhash_head	node;
  };

  struct thread_data {
  	int id;
  	struct task_struct *task;
  	struct test_obj *objs;
  };

  static struct test_obj array[MAX_ENTRIES];

  static struct rhashtable_params test_rht_params = {

  	.head_offset = offsetof(struct test_obj, node),
  	.key_offset = offsetof(struct test_obj, value),
  	.key_len = sizeof(int),
  	.hashfn = jhash,

  	.nulls_base = (3U << RHT_BASE_SHIFT),
  };

  static struct semaphore prestart_sem;
  static struct semaphore startup_sem = __SEMAPHORE_INITIALIZER(startup_sem, 0);

  static int insert_retry(struct rhashtable *ht, struct rhash_head *obj,
                          const struct rhashtable_params params)
  {

  	int err, retries = -1, enomem_retries = 0;

  
  	do {
  		retries++;
  		cond_resched();
  		err = rhashtable_insert_fast(ht, obj, params);

  		if (err == -ENOMEM && enomem_retry) {
  			enomem_retries++;
  			err = -EBUSY;
  		}

  	} while (err == -EBUSY);

  	if (enomem_retries)
  		pr_info(" %u insertions retried after -ENOMEM
  ",
  			enomem_retries);

  	return err ? : retries;
  }

  static int __init test_rht_lookup(struct rhashtable *ht)
  {
  	unsigned int i;

  	for (i = 0; i < entries * 2; i++) {

  		struct test_obj *obj;
  		bool expected = !(i % 2);
  		u32 key = i;

  		if (array[i / 2].value == TEST_INSERT_FAIL)
  			expected = false;

  		obj = rhashtable_lookup_fast(ht, &key, test_rht_params);

  
  		if (expected && !obj) {
  			pr_warn("Test failed: Could not find key %u
  ", key);
  			return -ENOENT;
  		} else if (!expected && obj) {
  			pr_warn("Test failed: Unexpected entry found for key %u
  ",
  				key);
  			return -EEXIST;
  		} else if (expected && obj) {

  			if (obj->value != i) {
  				pr_warn("Test failed: Lookup value mismatch %u!=%u
  ",
  					obj->value, i);

  				return -EINVAL;
  			}
  		}

  
  		cond_resched_rcu();

  	}
  
  	return 0;
  }

  static void test_bucket_stats(struct rhashtable *ht)

  {

  	unsigned int err, total = 0, chain_len = 0;
  	struct rhashtable_iter hti;

  	struct rhash_head *pos;

  	err = rhashtable_walk_init(ht, &hti, GFP_KERNEL);

  	if (err) {
  		pr_warn("Test failed: allocation error");
  		return;
  	}

  	err = rhashtable_walk_start(&hti);
  	if (err && err != -EAGAIN) {
  		pr_warn("Test failed: iterator failed: %d
  ", err);
  		return;
  	}

  	while ((pos = rhashtable_walk_next(&hti))) {
  		if (PTR_ERR(pos) == -EAGAIN) {
  			pr_info("Info: encountered resize
  ");
  			chain_len++;
  			continue;
  		} else if (IS_ERR(pos)) {
  			pr_warn("Test failed: rhashtable_walk_next() error: %ld
  ",
  				PTR_ERR(pos));
  			break;

  		}

  		total++;

  	}

  	rhashtable_walk_stop(&hti);
  	rhashtable_walk_exit(&hti);
  
  	pr_info("  Traversal complete: counted=%u, nelems=%u, entries=%d, table-jumps=%u
  ",
  		total, atomic_read(&ht->nelems), entries, chain_len);

  	if (total != atomic_read(&ht->nelems) || total != entries)

  		pr_warn("Test failed: Total count mismatch ^^^");
  }

  static s64 __init test_rhashtable(struct rhashtable *ht)

  {

  	struct test_obj *obj;

  	int err;

  	unsigned int i, insert_retries = 0;

  	s64 start, end;

  
  	/*
  	 * Insertion Test:

  	 * Insert entries into table with all keys even numbers

  	 */

  	pr_info("  Adding %d keys
  ", entries);
  	start = ktime_get_ns();
  	for (i = 0; i < entries; i++) {

  		struct test_obj *obj = &array[i];

  		obj->value = i * 2;

  		err = insert_retry(ht, &obj->node, test_rht_params);
  		if (err > 0)
  			insert_retries += err;
  		else if (err)

  			return err;

  	}

  	if (insert_retries)
  		pr_info("  %u insertions retried due to memory pressure
  ",
  			insert_retries);

  	test_bucket_stats(ht);

  	rcu_read_lock();

  	test_rht_lookup(ht);
  	rcu_read_unlock();

  	test_bucket_stats(ht);

  	pr_info("  Deleting %d keys
  ", entries);
  	for (i = 0; i < entries; i++) {

  		u32 key = i * 2;

  		if (array[i].value != TEST_INSERT_FAIL) {
  			obj = rhashtable_lookup_fast(ht, &key, test_rht_params);
  			BUG_ON(!obj);

  			rhashtable_remove_fast(ht, &obj->node, test_rht_params);
  		}

  
  		cond_resched();

  	}

  	end = ktime_get_ns();
  	pr_info("  Duration of test: %lld ns
  ", end - start);
  
  	return end - start;

  }

  static struct rhashtable ht;

  static int thread_lookup_test(struct thread_data *tdata)
  {
  	int i, err = 0;
  
  	for (i = 0; i < entries; i++) {
  		struct test_obj *obj;
  		int key = (tdata->id << 16) | i;
  
  		obj = rhashtable_lookup_fast(&ht, &key, test_rht_params);
  		if (obj && (tdata->objs[i].value == TEST_INSERT_FAIL)) {
  			pr_err("  found unexpected object %d
  ", key);
  			err++;
  		} else if (!obj && (tdata->objs[i].value != TEST_INSERT_FAIL)) {
  			pr_err("  object %d not found!
  ", key);
  			err++;
  		} else if (obj && (obj->value != key)) {
  			pr_err("  wrong object returned (got %d, expected %d)
  ",
  			       obj->value, key);
  			err++;
  		}

  
  		cond_resched();

  	}
  	return err;
  }
  
  static int threadfunc(void *data)
  {

  	int i, step, err = 0, insert_retries = 0;

  	struct thread_data *tdata = data;
  
  	up(&prestart_sem);
  	if (down_interruptible(&startup_sem))
  		pr_err("  thread[%d]: down_interruptible failed
  ", tdata->id);
  
  	for (i = 0; i < entries; i++) {
  		tdata->objs[i].value = (tdata->id << 16) | i;

  		err = insert_retry(&ht, &tdata->objs[i].node, test_rht_params);
  		if (err > 0) {
  			insert_retries += err;

  		} else if (err) {
  			pr_err("  thread[%d]: rhashtable_insert_fast failed
  ",
  			       tdata->id);
  			goto out;
  		}
  	}

  	if (insert_retries)
  		pr_info("  thread[%d]: %u insertions retried due to memory pressure
  ",
  			tdata->id, insert_retries);

  
  	err = thread_lookup_test(tdata);
  	if (err) {
  		pr_err("  thread[%d]: rhashtable_lookup_test failed
  ",
  		       tdata->id);
  		goto out;
  	}
  
  	for (step = 10; step > 0; step--) {
  		for (i = 0; i < entries; i += step) {
  			if (tdata->objs[i].value == TEST_INSERT_FAIL)
  				continue;
  			err = rhashtable_remove_fast(&ht, &tdata->objs[i].node,
  			                             test_rht_params);
  			if (err) {
  				pr_err("  thread[%d]: rhashtable_remove_fast failed
  ",
  				       tdata->id);
  				goto out;
  			}
  			tdata->objs[i].value = TEST_INSERT_FAIL;

  
  			cond_resched();

  		}
  		err = thread_lookup_test(tdata);
  		if (err) {
  			pr_err("  thread[%d]: rhashtable_lookup_test (2) failed
  ",
  			       tdata->id);
  			goto out;
  		}
  	}
  out:
  	while (!kthread_should_stop()) {
  		set_current_state(TASK_INTERRUPTIBLE);
  		schedule();
  	}
  	return err;
  }

  static int __init test_rht_init(void)
  {

  	int i, err, started_threads = 0, failed_threads = 0;

  	u64 total_time = 0;

  	struct thread_data *tdata;
  	struct test_obj *objs;

  	entries = min(entries, MAX_ENTRIES);

  	test_rht_params.automatic_shrinking = shrinking;

  	test_rht_params.max_size = max_size ? : roundup_pow_of_two(entries);

  	test_rht_params.nelem_hint = size;

  	pr_info("Running rhashtable test nelem=%d, max_size=%d, shrinking=%d
  ",
  		size, max_size, shrinking);

  	for (i = 0; i < runs; i++) {
  		s64 time;

  		pr_info("Test %02d:
  ", i);

  		memset(&array, 0, sizeof(array));

  		err = rhashtable_init(&ht, &test_rht_params);
  		if (err < 0) {
  			pr_warn("Test failed: Unable to initialize hashtable: %d
  ",
  				err);
  			continue;
  		}
  
  		time = test_rhashtable(&ht);
  		rhashtable_destroy(&ht);
  		if (time < 0) {
  			pr_warn("Test failed: return code %lld
  ", time);
  			return -EINVAL;
  		}
  
  		total_time += time;
  	}

  	do_div(total_time, runs);
  	pr_info("Average test time: %llu
  ", total_time);

  	if (!tcount)
  		return 0;
  
  	pr_info("Testing concurrent rhashtable access from %d threads
  ",
  	        tcount);
  	sema_init(&prestart_sem, 1 - tcount);
  	tdata = vzalloc(tcount * sizeof(struct thread_data));
  	if (!tdata)
  		return -ENOMEM;
  	objs  = vzalloc(tcount * entries * sizeof(struct test_obj));
  	if (!objs) {
  		vfree(tdata);
  		return -ENOMEM;
  	}

  	test_rht_params.max_size = max_size ? :
  	                           roundup_pow_of_two(tcount * entries);

  	err = rhashtable_init(&ht, &test_rht_params);
  	if (err < 0) {
  		pr_warn("Test failed: Unable to initialize hashtable: %d
  ",
  			err);
  		vfree(tdata);
  		vfree(objs);
  		return -EINVAL;
  	}
  	for (i = 0; i < tcount; i++) {
  		tdata[i].id = i;
  		tdata[i].objs = objs + i * entries;
  		tdata[i].task = kthread_run(threadfunc, &tdata[i],
  		                            "rhashtable_thrad[%d]", i);
  		if (IS_ERR(tdata[i].task))
  			pr_err(" kthread_run failed for thread %d
  ", i);
  		else
  			started_threads++;
  	}
  	if (down_interruptible(&prestart_sem))
  		pr_err("  down interruptible failed
  ");
  	for (i = 0; i < tcount; i++)
  		up(&startup_sem);
  	for (i = 0; i < tcount; i++) {
  		if (IS_ERR(tdata[i].task))
  			continue;
  		if ((err = kthread_stop(tdata[i].task))) {
  			pr_warn("Test failed: thread %d returned: %d
  ",
  			        i, err);
  			failed_threads++;
  		}
  	}
  	pr_info("Started %d threads, %d failed
  ",
  	        started_threads, failed_threads);
  	rhashtable_destroy(&ht);
  	vfree(tdata);
  	vfree(objs);

  	return 0;

  }

  static void __exit test_rht_exit(void)
  {
  }

  module_init(test_rht_init);

  module_exit(test_rht_exit);

  
  MODULE_LICENSE("GPL v2");