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arts/flow/gsl/gsldatacache.c

634 lines
18 KiB

/* GSL - Generic Sound Layer
* Copyright (C) 2001-2002 Tim Janik
* Copyright (C) 2004 Stefan Westerfeld
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General
* Public License along with this library; if not, write to the
* Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*/
#include "gsldatacache.h"
#include "gslcommon.h"
#include "gsldatahandle.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <time.h>
/* --- macros --- */
#define NODEP_INDEX(dcache, node_p) ((node_p) - (dcache)->nodes)
#define UPPER_POWER2(n) (gsl_alloc_upper_power2 (MAX (n, 4)))
#define CONFIG_NODE_SIZE() (gsl_get_config ()->dcache_block_size)
#define AGE_EPSILON (3) /* must be < smallest sweep */
#define LOW_PERSISTENCY_SWEEP (5)
/* we use one global lock to protect the dcache list, the list
* count (length) and the number of aged (unused) nodes.
* also, each dcache has its own mutext to protect updates in
* the reference count, nodes or node data blocks.
* in order to avoid deadlocks, if both locks need
* to be held, they always have to be acquired in the order
* 1) global lock, 2) dcache lock.
* asyncronous data block filling for a new node occours without
* the dcache lock being held (as most calls to GslDataHandle
* functions).
* however, assignment of the newly acquired data is again
* protected by the dcache lock. concurrent API entries
* which require demand loading of such data will wait on
* a global condition which is always signaled once a new data
* block read has been completed. using one global condition
* is considered sufficient until shown otherwise by further
* profiling/debugging measures.
*/
/* --- prototypes --- */
static void dcache_free (GslDataCache *dcache);
static GslDataCacheNode* data_cache_new_node_L (GslDataCache *dcache,
gsize offset,
guint pos,
gboolean demand_load);
/* --- variables --- */
static GslMutex global_dcache_mutex = { 0, };
static GslCond global_dcache_cond_node_filled = { 0, };
static GslRing *global_dcache_list = NULL;
static guint global_dcache_count = 0;
static guint global_dcache_n_aged_nodes = 0;
/* --- functions --- */
void
_gsl_init_data_caches (void)
{
static gboolean initialized = FALSE;
g_assert (initialized == FALSE);
initialized++;
g_assert (AGE_EPSILON < LOW_PERSISTENCY_SWEEP);
gsl_cond_init (&global_dcache_cond_node_filled);
gsl_mutex_init (&global_dcache_mutex);
}
GslDataCache*
gsl_data_cache_new (GslDataHandle *dhandle,
guint padding)
{
guint node_size = CONFIG_NODE_SIZE () / sizeof (GslDataType);
GslDataCache *dcache;
g_return_val_if_fail (dhandle != NULL, NULL);
g_return_val_if_fail (padding > 0, NULL);
g_return_val_if_fail (dhandle->name != NULL, NULL);
g_assert (node_size == gsl_alloc_upper_power2 (node_size));
g_return_val_if_fail (padding < node_size / 2, NULL);
/* allocate new closed dcache if necessary */
dcache = gsl_new_struct (GslDataCache, 1);
dcache->dhandle = gsl_data_handle_ref (dhandle);
dcache->open_count = 0;
gsl_mutex_init (&dcache->mutex);
dcache->ref_count = 1;
dcache->node_size = node_size;
dcache->padding = padding;
dcache->max_age = 0;
dcache->low_persistency = FALSE; /* FIXME: !gsl_data_handle_needs_cache (dcache->dhandle); */
dcache->n_nodes = 0;
dcache->nodes = g_renew (GslDataCacheNode*, NULL, UPPER_POWER2 (dcache->n_nodes));
GSL_SPIN_LOCK (&global_dcache_mutex);
global_dcache_list = gsl_ring_append (global_dcache_list, dcache);
global_dcache_count++;
GSL_SPIN_UNLOCK (&global_dcache_mutex);
return dcache;
}
void
gsl_data_cache_open (GslDataCache *dcache)
{
g_return_if_fail (dcache != NULL);
g_return_if_fail (dcache->ref_count > 0);
GSL_SPIN_LOCK (&dcache->mutex);
if (!dcache->open_count)
{
GslErrorType error;
error = gsl_data_handle_open (dcache->dhandle);
if (error)
{
/* FIXME: this is pretty fatal, throw out zero blocks now? */
gsl_message_send (GSL_MSG_DATA_CACHE, "Open",
error,
"failed to open \"%s\": %s",
dcache->dhandle->name,
gsl_strerror (error));
}
else
{
dcache->open_count = 1;
dcache->ref_count++;
}
}
else
dcache->open_count++;
GSL_SPIN_UNLOCK (&dcache->mutex);
}
void
gsl_data_cache_close (GslDataCache *dcache)
{
gboolean need_unref;
g_return_if_fail (dcache != NULL);
g_return_if_fail (dcache->ref_count > 0);
g_return_if_fail (dcache->open_count > 0);
GSL_SPIN_LOCK (&dcache->mutex);
dcache->open_count--;
need_unref = !dcache->open_count;
if (!dcache->open_count)
gsl_data_handle_close (dcache->dhandle);
GSL_SPIN_UNLOCK (&dcache->mutex);
if (need_unref)
gsl_data_cache_unref (dcache);
}
GslDataCache*
gsl_data_cache_ref (GslDataCache *dcache)
{
g_return_val_if_fail (dcache != NULL, NULL);
g_return_val_if_fail (dcache->ref_count > 0, NULL);
/* we might get invoked with global_dcache_mutex locked */
GSL_SPIN_LOCK (&dcache->mutex);
dcache->ref_count++;
GSL_SPIN_UNLOCK (&dcache->mutex);
return dcache;
}
static void
dcache_free (GslDataCache *dcache)
{
guint i;
g_return_if_fail (dcache->ref_count == 0);
g_return_if_fail (dcache->open_count == 0);
gsl_data_handle_unref (dcache->dhandle);
gsl_mutex_destroy (&dcache->mutex);
for (i = 0; i < dcache->n_nodes; i++)
{
GslDataCacheNode *node = dcache->nodes[i];
guint size;
size = dcache->node_size + (dcache->padding << 1);
gsl_delete_structs (GslDataType, size, node->data - dcache->padding);
gsl_delete_struct (GslDataCacheNode, node);
}
g_free (dcache->nodes);
gsl_delete_struct (GslDataCache, dcache);
}
void
gsl_data_cache_unref (GslDataCache *dcache)
{
g_return_if_fail (dcache != NULL);
restart:
g_return_if_fail (dcache->ref_count > 0);
if (dcache->ref_count == 1) /* possible destruction, need global lock */
{
g_return_if_fail (dcache->open_count == 0);
GSL_SPIN_LOCK (&global_dcache_mutex);
GSL_SPIN_LOCK (&dcache->mutex);
if (dcache->ref_count != 1)
{
/* damn, some other thread trapped in, restart */
GSL_SPIN_UNLOCK (&dcache->mutex);
GSL_SPIN_UNLOCK (&global_dcache_mutex);
goto restart;
}
dcache->ref_count = 0;
global_dcache_list = gsl_ring_remove (global_dcache_list, dcache);
GSL_SPIN_UNLOCK (&dcache->mutex);
global_dcache_count--;
global_dcache_n_aged_nodes -= dcache->n_nodes;
GSL_SPIN_UNLOCK (&global_dcache_mutex);
dcache_free (dcache);
}
else
{
GSL_SPIN_LOCK (&dcache->mutex);
if (dcache->ref_count < 2)
{
/* damn, some other thread trapped in, restart */
GSL_SPIN_UNLOCK (&dcache->mutex);
goto restart;
}
dcache->ref_count--;
GSL_SPIN_UNLOCK (&dcache->mutex);
}
}
static inline GslDataCacheNode**
data_cache_lookup_nextmost_node_L (GslDataCache *dcache,
gsize offset)
{
if (dcache->n_nodes > 0)
{
GslDataCacheNode **check, **nodes = dcache->nodes;
guint n_nodes = dcache->n_nodes, node_size = dcache->node_size;
/* caller has to figure himself whether we return nextmost vs. exact match */
nodes -= 1;
do
{
register gint cmp;
register guint i;
i = (n_nodes + 1) >> 1;
check = nodes + i;
cmp = offset < (*check)->offset ? -1 : offset >= (*check)->offset + node_size;
if (cmp == 0)
return check; /* exact match */
else if (cmp > 0)
{
n_nodes -= i;
nodes = check;
}
else /* if (cmp < 0) */
n_nodes = i - 1;
}
while (n_nodes);
return check; /* nextmost */
}
return NULL;
}
static inline GslDataCacheNode*
data_cache_new_node_L (GslDataCache *dcache,
gsize offset,
guint pos,
gboolean demand_load)
{
GslDataCacheNode **node_p, *dnode;
GslDataCacheNode *left_node;
GslDataType *data, *node_data;
guint new_node_array_size, old_node_array_size = UPPER_POWER2 (dcache->n_nodes);
GslLong dhandle_length;
guint i, size;
gint result;
i = dcache->n_nodes++;
new_node_array_size = UPPER_POWER2 (dcache->n_nodes);
if (old_node_array_size != new_node_array_size)
dcache->nodes = g_renew (GslDataCacheNode*, dcache->nodes, new_node_array_size);
node_p = dcache->nodes + pos;
g_memmove (node_p + 1, node_p, (i - pos) * sizeof (*node_p));
dnode = gsl_new_struct (GslDataCacheNode, 1);
(*node_p) = dnode;
dnode->offset = offset & ~(dcache->node_size - 1);
dnode->ref_count = 1;
dnode->age = 0;
dnode->data = NULL;
GSL_SPIN_UNLOCK (&dcache->mutex);
size = dcache->node_size + (dcache->padding << 1);
data = gsl_new_struct (GslDataType, size);
node_data = data + dcache->padding;
offset = dnode->offset;
if (dcache->padding > offset) /* pad out bytes before data start */
{
guint short_pad = dcache->padding - offset;
memset (data, 0, short_pad * sizeof (GslDataType));
size -= short_pad;
data += short_pad;
offset -= (dcache->padding - short_pad); /* should always result in offset=0 */
}
else
offset -= dcache->padding;
if (!demand_load)
g_message (G_STRLOC ":FIXME: lazy data loading not yet supported");
/* if we have a left node, and it tqcontains data that we need, copy it */
left_node = pos ? dcache->nodes[pos - 1] : NULL;
if (left_node)
{
guint left_node_size = dcache->node_size;
gint left_node_offset = left_node->offset;
GslDataType *left_node_data = left_node->data;
/* padding around left_node */
left_node_size += (dcache->padding << 1);
left_node_offset -= dcache->padding;
left_node_data -= dcache->padding;
if (offset < left_node_offset + left_node_size)
{
guint left_node_copy = left_node_offset + left_node_size - offset;
memcpy (data, left_node_data + offset - left_node_offset,
left_node_copy * sizeof (GslDataType));
offset += left_node_copy;
size -= left_node_copy;
data += left_node_copy;
}
}
dhandle_length = gsl_data_handle_length (dcache->dhandle);
do
{
if (offset >= dhandle_length)
break;
size = MIN (size, dhandle_length - offset);
result = gsl_data_handle_read (dcache->dhandle, offset, size, data);
if (result < 0)
{
gsl_message_send (GSL_MSG_DATA_CACHE, "ReadAhead",
GSL_ERROR_READ_FAILED,
"reading from \"%s\"", dcache->dhandle->name);
break;
}
else
{
offset += result;
size -= result;
data += result;
}
}
while (size && result > 0);
memset (data, 0, size * sizeof (data[0]));
GSL_SPIN_LOCK (&dcache->mutex);
dnode->data = node_data;
gsl_cond_broadcast (&global_dcache_cond_node_filled);
return dnode;
}
GslDataCacheNode*
gsl_data_cache_ref_node (GslDataCache *dcache,
gsize offset,
GslDataCacheRequest load_request)
{
GslDataCacheNode **node_p, *node;
guint insertion_pos;
g_return_val_if_fail (dcache != NULL, NULL);
g_return_val_if_fail (dcache->ref_count > 0, NULL);
g_return_val_if_fail (dcache->open_count > 0, NULL);
g_return_val_if_fail (offset < gsl_data_handle_length (dcache->dhandle), NULL);
GSL_SPIN_LOCK (&dcache->mutex);
node_p = data_cache_lookup_nextmost_node_L (dcache, offset);
if (node_p)
{
node = *node_p;
if (offset >= node->offset && offset < node->offset + dcache->node_size)
{
gboolean rejuvenate_node = !node->ref_count;
if (load_request == GSL_DATA_CACHE_PEEK)
{
if (node->data)
node->ref_count++;
else
node = NULL;
GSL_SPIN_UNLOCK (&dcache->mutex);
if (node && rejuvenate_node)
{
GSL_SPIN_LOCK (&global_dcache_mutex); /* different lock */
global_dcache_n_aged_nodes--;
GSL_SPIN_UNLOCK (&global_dcache_mutex);
}
return node;
}
node->ref_count++;
if (load_request == GSL_DATA_CACHE_DEMAND_LOAD)
while (!node->data)
gsl_cond_wait (&global_dcache_cond_node_filled, &dcache->mutex);
GSL_SPIN_UNLOCK (&dcache->mutex);
/* g_printerr ("hit: %d :%d: %d\n", node->offset, offset, node->offset + dcache->node_size); */
if (rejuvenate_node)
{
GSL_SPIN_LOCK (&global_dcache_mutex); /* different lock */
global_dcache_n_aged_nodes--;
GSL_SPIN_UNLOCK (&global_dcache_mutex);
}
return node; /* exact match */
}
insertion_pos = NODEP_INDEX (dcache, node_p); /* insert before neighbour */
if (offset > node->offset) /* insert after neighbour */
insertion_pos += 1;
/* g_printerr ("mis: %d :%d: %d\n", node->offset, offset, node->offset + dcache->node_size); */
}
else
insertion_pos = 0; /* insert at start */
if (load_request != GSL_DATA_CACHE_PEEK)
node = data_cache_new_node_L (dcache, offset, insertion_pos, load_request == GSL_DATA_CACHE_DEMAND_LOAD);
else
node = NULL;
GSL_SPIN_UNLOCK (&dcache->mutex);
return node;
}
static gboolean /* still locked */
data_cache_free_olders_Lunlock (GslDataCache *dcache,
guint max_lru) /* how many lru nodes to keep */
{
GslDataCacheNode **slot_p;
guint i, rejuvenate, size;
guint n_freed = 0;
g_return_val_if_fail (dcache != NULL, TRUE);
/* it doesn't make sense to free nodes below the jitter that
* AGE_EPSILON attempts to prevent.
*/
max_lru = MAX (AGE_EPSILON, max_lru);
if (max_lru >= dcache->max_age)
return TRUE;
rejuvenate = dcache->max_age - max_lru;
if (0)
g_print ("start sweep: dcache (%p) with %u nodes, max_age: %u, rejuvenate: %u (max_lru: %u)\n",
dcache, dcache->n_nodes, dcache->max_age, rejuvenate, max_lru);
size = dcache->node_size + (dcache->padding << 1);
slot_p = NULL;
for (i = 0; i < dcache->n_nodes; i++)
{
GslDataCacheNode *node = dcache->nodes[i];
if (!node->ref_count && node->age <= rejuvenate)
{
gsl_delete_structs (GslDataType, size, node->data - dcache->padding);
gsl_delete_struct (GslDataCacheNode, node);
if (!slot_p)
slot_p = dcache->nodes + i;
n_freed++;
}
else
{
node->age -= MIN (rejuvenate, node->age);
if (slot_p)
{
*slot_p = node;
slot_p++;
}
}
}
dcache->max_age = max_lru;
if (slot_p)
dcache->n_nodes = NODEP_INDEX (dcache, slot_p);
GSL_SPIN_UNLOCK (&dcache->mutex);
if (n_freed)
{
GSL_SPIN_LOCK (&global_dcache_mutex);
global_dcache_n_aged_nodes -= n_freed;
GSL_SPIN_UNLOCK (&global_dcache_mutex);
}
if (0)
g_printerr ("freed %u nodes (%u bytes) remaining %u bytes\n",
n_freed, n_freed * CONFIG_NODE_SIZE (),
global_dcache_n_aged_nodes * CONFIG_NODE_SIZE ());
return FALSE;
}
void
gsl_data_cache_unref_node (GslDataCache *dcache,
GslDataCacheNode *node)
{
GslDataCacheNode **node_p;
gboolean check_cache;
g_return_if_fail (dcache != NULL);
g_return_if_fail (node != NULL);
g_return_if_fail (node->ref_count > 0);
GSL_SPIN_LOCK (&dcache->mutex);
node_p = data_cache_lookup_nextmost_node_L (dcache, node->offset);
g_assert (node_p && *node_p == node); /* paranoid check lookup, yeah! */
node->ref_count -= 1;
check_cache = !node->ref_count;
if (!node->ref_count &&
(node->age + AGE_EPSILON <= dcache->max_age ||
dcache->max_age < AGE_EPSILON))
node->age = ++dcache->max_age;
GSL_SPIN_UNLOCK (&dcache->mutex);
if (check_cache)
{
guint node_size = CONFIG_NODE_SIZE ();
guint cache_mem = gsl_get_config ()->dcache_cache_memory;
guint current_mem;
/* FIXME: cache sweeping should not be done from _unref_node for high persistency caches */
GSL_SPIN_LOCK (&global_dcache_mutex);
global_dcache_n_aged_nodes++;
current_mem = node_size * global_dcache_n_aged_nodes;
if (current_mem > cache_mem)
{
guint dcache_count, needs_unlock;
dcache = gsl_ring_pop_head (&global_dcache_list);
GSL_SPIN_LOCK (&dcache->mutex);
dcache->ref_count++;
global_dcache_list = gsl_ring_append (global_dcache_list, dcache);
dcache_count = global_dcache_count;
GSL_SPIN_UNLOCK (&global_dcache_mutex);
if (dcache->low_persistency)
needs_unlock = data_cache_free_olders_Lunlock (dcache, LOW_PERSISTENCY_SWEEP);
else
{
guint max_lru;
/* try to free the actual cache overflow from the
* dcache we just picked, but don't free more than
* 25% of its nodes yet.
* overflow is actual overhang + ~6% of cache size,
* so cache sweeps are triggered less frequently.
*/
current_mem -= cache_mem; /* overhang */
current_mem += cache_mem >> 4; /* overflow = overhang + 6% */
current_mem /= node_size; /* n_nodes to free */
current_mem = MIN (current_mem, dcache->n_nodes);
max_lru = dcache->n_nodes >> 1;
max_lru += max_lru >> 1; /* 75% of n_nodes */
max_lru = MAX (max_lru, dcache->n_nodes - current_mem);
needs_unlock = data_cache_free_olders_Lunlock (dcache, MAX (max_lru, LOW_PERSISTENCY_SWEEP));
}
if (needs_unlock)
GSL_SPIN_UNLOCK (&dcache->mutex);
}
else
GSL_SPIN_UNLOCK (&global_dcache_mutex);
}
}
void
gsl_data_cache_free_olders (GslDataCache *dcache,
guint max_age)
{
gboolean needs_unlock;
g_return_if_fail (dcache != NULL);
GSL_SPIN_LOCK (&dcache->mutex);
needs_unlock = data_cache_free_olders_Lunlock (dcache, max_age);
if (needs_unlock)
GSL_SPIN_UNLOCK (&dcache->mutex);
}
GslDataCache*
gsl_data_cache_from_dhandle (GslDataHandle *dhandle,
guint min_padding)
{
GslRing *ring;
g_return_val_if_fail (dhandle != NULL, NULL);
GSL_SPIN_LOCK (&global_dcache_mutex);
for (ring = global_dcache_list; ring; ring = gsl_ring_walk (global_dcache_list, ring))
{
GslDataCache *dcache = ring->data;
if (dcache->dhandle == dhandle && dcache->padding >= min_padding)
{
gsl_data_cache_ref (dcache);
GSL_SPIN_UNLOCK (&global_dcache_mutex);
return dcache;
}
}
GSL_SPIN_UNLOCK (&global_dcache_mutex);
return gsl_data_cache_new (dhandle, min_padding);
}