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-rw-r--r--erts/emulator/beam/code_ix.c168
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diff --git a/erts/emulator/beam/code_ix.c b/erts/emulator/beam/code_ix.c
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+/*
+ * %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 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");
+#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
+ 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_smp_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_smp_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