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/*
* %CopyrightBegin%
*
* Copyright Ericsson AB 2012-2016. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* %CopyrightEnd%
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#include "code_ix.h"
#include "global.h"
#include "beam_catches.h"
#if 0
# define CIX_TRACE(text) erts_fprintf(stderr, "CIX_TRACE: " text " act=%u load=%u\r\n", erts_active_code_ix(), erts_staging_code_ix())
#else
# define CIX_TRACE(text)
#endif
erts_smp_atomic32_t the_active_code_index;
erts_smp_atomic32_t the_staging_code_index;
static Process* code_writing_process = NULL;
struct code_write_queue_item {
Process *p;
struct code_write_queue_item* next;
};
static struct code_write_queue_item* code_write_queue = NULL;
static erts_smp_mtx_t code_write_permission_mtx;
#ifdef ERTS_ENABLE_LOCK_CHECK
static erts_tsd_key_t has_code_write_permission;
#endif
void erts_code_ix_init(void)
{
/* We start emulator by initializing preloaded modules
* single threaded with active and staging set both to zero.
* Preloading is finished by a commit that will set things straight.
*/
erts_smp_atomic32_init_nob(&the_active_code_index, 0);
erts_smp_atomic32_init_nob(&the_staging_code_index, 0);
erts_smp_mtx_init(&code_write_permission_mtx, "code_write_permission", NIL,
ERTS_LOCK_FLAGS_PROPERTY_STATIC | ERTS_LOCK_FLAGS_CATEGORY_GENERIC);
#ifdef ERTS_ENABLE_LOCK_CHECK
erts_tsd_key_create(&has_code_write_permission,
"erts_has_code_write_permission");
#endif
CIX_TRACE("init");
}
void erts_start_staging_code_ix(int num_new)
{
beam_catches_start_staging();
export_start_staging();
module_start_staging();
erts_start_staging_ranges(num_new);
CIX_TRACE("start");
}
void erts_end_staging_code_ix(void)
{
beam_catches_end_staging(1);
export_end_staging(1);
module_end_staging(1);
erts_end_staging_ranges(1);
CIX_TRACE("end");
}
void erts_commit_staging_code_ix(void)
{
ErtsCodeIndex ix;
/* We need to this lock as we are now making the staging export table active */
export_staging_lock();
ix = erts_staging_code_ix();
erts_smp_atomic32_set_nob(&the_active_code_index, ix);
ix = (ix + 1) % ERTS_NUM_CODE_IX;
erts_smp_atomic32_set_nob(&the_staging_code_index, ix);
export_staging_unlock();
erts_tracer_nif_clear();
CIX_TRACE("activate");
}
void erts_abort_staging_code_ix(void)
{
beam_catches_end_staging(0);
export_end_staging(0);
module_end_staging(0);
erts_end_staging_ranges(0);
CIX_TRACE("abort");
}
/*
* Calller _must_ yield if we return 0
*/
int erts_try_seize_code_write_permission(Process* c_p)
{
int success;
#ifdef ERTS_SMP
ASSERT(!erts_smp_thr_progress_is_blocking()); /* to avoid deadlock */
#endif
ASSERT(c_p != NULL);
erts_smp_mtx_lock(&code_write_permission_mtx);
success = (code_writing_process == NULL);
if (success) {
code_writing_process = c_p;
#ifdef ERTS_ENABLE_LOCK_CHECK
erts_tsd_set(has_code_write_permission, (void *) 1);
#endif
}
else { /* Already locked */
struct code_write_queue_item* qitem;
ASSERT(code_writing_process != c_p);
qitem = erts_alloc(ERTS_ALC_T_CODE_IX_LOCK_Q, sizeof(*qitem));
qitem->p = c_p;
erts_proc_inc_refc(c_p);
qitem->next = code_write_queue;
code_write_queue = qitem;
erts_suspend(c_p, ERTS_PROC_LOCK_MAIN, NULL);
}
erts_smp_mtx_unlock(&code_write_permission_mtx);
return success;
}
void erts_release_code_write_permission(void)
{
erts_smp_mtx_lock(&code_write_permission_mtx);
ERTS_SMP_LC_ASSERT(erts_has_code_write_permission());
while (code_write_queue != NULL) { /* unleash the entire herd */
struct code_write_queue_item* qitem = code_write_queue;
erts_smp_proc_lock(qitem->p, ERTS_PROC_LOCK_STATUS);
if (!ERTS_PROC_IS_EXITING(qitem->p)) {
erts_resume(qitem->p, ERTS_PROC_LOCK_STATUS);
}
erts_smp_proc_unlock(qitem->p, ERTS_PROC_LOCK_STATUS);
code_write_queue = qitem->next;
erts_proc_dec_refc(qitem->p);
erts_free(ERTS_ALC_T_CODE_IX_LOCK_Q, qitem);
}
code_writing_process = NULL;
#ifdef ERTS_ENABLE_LOCK_CHECK
erts_tsd_set(has_code_write_permission, (void *) 0);
#endif
erts_smp_mtx_unlock(&code_write_permission_mtx);
}
#ifdef ERTS_ENABLE_LOCK_CHECK
int erts_has_code_write_permission(void)
{
return (code_writing_process != NULL) && erts_tsd_get(has_code_write_permission);
}
#endif
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