diff options
Diffstat (limited to 'erts/emulator/beam/code_ix.c')
| -rw-r--r-- | erts/emulator/beam/code_ix.c | 166 |
1 files changed, 166 insertions, 0 deletions
diff --git a/erts/emulator/beam/code_ix.c b/erts/emulator/beam/code_ix.c new file mode 100644 index 0000000000..8025058ee0 --- /dev/null +++ b/erts/emulator/beam/code_ix.c @@ -0,0 +1,166 @@ +/* + * %CopyrightBegin% + * + * Copyright Ericsson AB 2012. All Rights Reserved. + * + * The contents of this file are subject to the Erlang Public License, + * Version 1.1, (the "License"); you may not use this file except in + * compliance with the License. You should have received a copy of the + * Erlang Public License along with this software. If not, it can be + * retrieved online at http://www.erlang.org/. + * + * Software distributed under the License is distributed on an "AS IS" + * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See + * the License for the specific language governing rights 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 int the_code_ix_lock = 0; +struct code_ix_queue_item { + Process *p; + struct code_ix_queue_item* next; +}; +static struct code_ix_queue_item* the_code_ix_queue = NULL; +static erts_smp_mtx_t the_code_ix_queue_lock; + +#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(&the_code_ix_queue_lock, "code_ix_queue"); +#ifdef ERTS_ENABLE_LOCK_CHECK + erts_tsd_key_create(&has_code_write_permission); +#endif + CIX_TRACE("init"); +} + +void erts_start_staging_code_ix(void) +{ + beam_catches_start_staging(); + export_start_staging(); + module_start_staging(); + erts_start_staging_ranges(); + 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(); + 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 + + erts_smp_mtx_lock(&the_code_ix_queue_lock); + success = !the_code_ix_lock; + if (success) { + the_code_ix_lock = 1; +#ifdef ERTS_ENABLE_LOCK_CHECK + erts_tsd_set(has_code_write_permission, (void *) 1); +#endif + } + else { /* Already locked */ + struct code_ix_queue_item* qitem; + qitem = erts_alloc(ERTS_ALC_T_CODE_IX_LOCK_Q, sizeof(*qitem)); + qitem->p = c_p; + erts_smp_proc_inc_refc(c_p); + qitem->next = the_code_ix_queue; + the_code_ix_queue = qitem; + erts_suspend(c_p, ERTS_PROC_LOCK_MAIN, NULL); + } + erts_smp_mtx_unlock(&the_code_ix_queue_lock); + return success; +} + +void erts_release_code_write_permission(void) +{ + ERTS_SMP_LC_ASSERT(erts_is_code_ix_locked()); + erts_smp_mtx_lock(&the_code_ix_queue_lock); + while (the_code_ix_queue != NULL) { /* unleash the entire herd */ + struct code_ix_queue_item* qitem = the_code_ix_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); + the_code_ix_queue = qitem->next; + erts_smp_proc_dec_refc(qitem->p); + erts_free(ERTS_ALC_T_CODE_IX_LOCK_Q, qitem); + } + the_code_ix_lock = 0; +#ifdef ERTS_ENABLE_LOCK_CHECK + erts_tsd_set(has_code_write_permission, (void *) 0); +#endif + erts_smp_mtx_unlock(&the_code_ix_queue_lock); +} + +#ifdef ERTS_ENABLE_LOCK_CHECK +int erts_is_code_ix_locked(void) +{ + return the_code_ix_lock && erts_tsd_get(has_code_write_permission); +} +#endif |