Process aliases

Signed-off-by: Mateusz Front <[email protected]>

Author: mat-hek

libs/estdlib/src/erlang.erl

@@ -99,6 +99,7 @@
     make_ref/0,
     send/2,
     monitor/2,
+    monitor/3,
     demonitor/1,
     demonitor/2,
     exit/1,
@@ -133,7 +134,9 @@
     dist_ctrl_put_data/2,
     unique_integer/0,
     unique_integer/1,
-    raise/3
+    raise/3,
+    alias/0,
+    unalias/1
 ]).
 
 -export_type([
@@ -1167,6 +1170,9 @@ send(_Target, _Message) ->
 monitor(_Type, _PidOrPort) ->
     erlang:nif_error(undefined).
 
+monitor(_Type, _PidOrPort, _Options) ->
+    erlang:nif_error(undefined).
+
 %%-----------------------------------------------------------------------------
 %% @param   Monitor reference of monitor to remove
 %% @returns `true'
@@ -1578,3 +1584,9 @@ nif_error(_Reason) ->
     no_return().
 raise(_Class, _Reason, _Stacktrace) ->
     erlang:nif_error(undefined).
+
+alias() ->
+    erlang:nif_error(undefined).
+
+unalias(_Alias) ->
+    erlang:nif_error(undefined).

src/libAtomVM/context.c

@@ -260,6 +260,7 @@ void context_destroy(Context *ctx)
                 case CONTEXT_MONITOR_MONITORED_LOCAL:
                 case CONTEXT_MONITOR_MONITORING_LOCAL:
                 case CONTEXT_MONITOR_MONITORING_LOCAL_REGISTEREDNAME:
+                case CONTEXT_MONITOR_ALIAS:
                     UNREACHABLE();
             }
         }
@@ -799,6 +800,9 @@ static struct Monitor *context_monitors_handle_terminate(Context *ctx)
                 free(monitor);
                 break;
             }
+            case CONTEXT_MONITOR_ALIAS: {
+                free(monitor);
+            }
         }
     }
     return result;
@@ -869,6 +873,19 @@ struct Monitor *monitor_registeredname_monitor_new(int32_t monitor_process_id, t
     return &monitor->monitor;
 }
 
+struct Monitor *monitor_alias_new(uint64_t ref_ticks, enum ContextMonitorAliasType alias_type)
+{
+    struct MonitorAlias *monitor = malloc(sizeof(struct MonitorAlias));
+    if (IS_NULL_PTR(monitor)) {
+        return NULL;
+    }
+    monitor->monitor.monitor_type = CONTEXT_MONITOR_ALIAS;
+    monitor->ref_ticks = ref_ticks;
+    monitor->alias_type = alias_type;
+
+    return &monitor->monitor;
+}
+
 struct Monitor *monitor_resource_monitor_new(void *resource, uint64_t ref_ticks)
 {
     struct ResourceContextMonitor *monitor = malloc(sizeof(struct ResourceContextMonitor));
@@ -920,6 +937,16 @@ bool context_add_monitor(Context *ctx, struct Monitor *new_monitor)
                     }
                     break;
                 }
+                case CONTEXT_MONITOR_ALIAS: {
+                    struct MonitorAlias *new_alias_monitor = CONTAINER_OF(new_monitor, struct MonitorAlias, monitor);
+                    struct MonitorAlias *existing_alias_monitor = CONTAINER_OF(existing, struct MonitorAlias, monitor);
+
+                    if (UNLIKELY(existing_alias_monitor->alias_type == new_alias_monitor->alias_type && existing_alias_monitor->ref_ticks == new_alias_monitor->ref_ticks)) {
+                        free(new_monitor);
+                        return false;
+                    }
+                    break;
+                }
                 case CONTEXT_MONITOR_RESOURCE: {
                     struct ResourceContextMonitor *new_resource_monitor = CONTAINER_OF(new_monitor, struct ResourceContextMonitor, monitor);
                     struct ResourceContextMonitor *existing_resource_monitor = CONTAINER_OF(existing, struct ResourceContextMonitor, monitor);
@@ -1053,6 +1080,8 @@ void context_unlink_ack(Context *ctx, term link_pid, uint64_t unlink_id)
 
 void context_demonitor(Context *ctx, uint64_t ref_ticks)
 {
+    context_unalias(ctx, ref_ticks, true);
+
     struct ListHead *item;
     LIST_FOR_EACH (item, &ctx->monitors_head) {
         struct Monitor *monitor = GET_LIST_ENTRY(item, struct Monitor, monitor_list_head);
@@ -1086,11 +1115,46 @@ void context_demonitor(Context *ctx, uint64_t ref_ticks)
             }
             case CONTEXT_MONITOR_LINK_LOCAL:
             case CONTEXT_MONITOR_LINK_REMOTE:
+            case CONTEXT_MONITOR_ALIAS:
                 break;
         }
     }
 }
 
+struct MonitorAlias *context_find_alias(Context *ctx, uint64_t ref_ticks)
+{
+    struct ListHead *item;
+    LIST_FOR_EACH (item, &ctx->monitors_head) {
+        struct Monitor *monitor = GET_LIST_ENTRY(item, struct Monitor, monitor_list_head);
+        if (monitor->monitor_type == CONTEXT_MONITOR_ALIAS) {
+            struct MonitorAlias *alias_monitor = CONTAINER_OF(monitor, struct MonitorAlias, monitor);
+            if (alias_monitor->ref_ticks == ref_ticks) {
+                return alias_monitor;
+            }
+        }
+    }
+
+    return NULL;
+}
+
+bool context_unalias(Context *ctx, uint64_t ref_ticks, bool from_demonitor)
+{
+    struct MonitorAlias *alias_monitor = context_find_alias(ctx, ref_ticks);
+    if (IS_NULL_PTR(alias_monitor)) {
+        return false;
+    }
+
+    if (alias_monitor->alias_type == CONTEXT_MONITOR_ALIAS_DEMONITOR
+        || (alias_monitor->alias_type == CONTEXT_MONITOR_ALIAS_EXPLICIT_UNALIAS && !from_demonitor)) {
+        struct Monitor *monitor = &alias_monitor->monitor;
+        list_remove(&monitor->monitor_list_head);
+        free(monitor);
+        return true;
+    } else {
+        return false;
+    }
+}
+
 term context_get_monitor_pid(Context *ctx, uint64_t ref_ticks, bool *is_monitoring)
 {
     struct ListHead *item;
@@ -1117,6 +1181,7 @@ term context_get_monitor_pid(Context *ctx, uint64_t ref_ticks, bool *is_monitori
             case CONTEXT_MONITOR_LINK_LOCAL:
             case CONTEXT_MONITOR_LINK_REMOTE:
             case CONTEXT_MONITOR_RESOURCE:
+            case CONTEXT_MONITOR_ALIAS:
                 break;
         }
     }
@@ -1246,6 +1311,12 @@ COLD_FUNC void context_dump(Context *ctx)
                 fprintf(stderr, "\n");
                 break;
             }
+            case CONTEXT_MONITOR_ALIAS: {
+                struct MonitorLocalMonitor *monitored_monitor = CONTAINER_OF(monitor, struct MonitorLocalMonitor, monitor);
+                fprintf(stderr, "has alias ref=%lu", (long unsigned) monitored_monitor->ref_ticks);
+                fprintf(stderr, "\n");
+                break;
+            }
             case CONTEXT_MONITOR_MONITORED_LOCAL: {
                 struct MonitorLocalMonitor *monitored_monitor = CONTAINER_OF(monitor, struct MonitorLocalMonitor, monitor);
                 fprintf(stderr, "monitored by ");

src/libAtomVM/context.h

@@ -172,6 +172,13 @@ enum ContextMonitorType
     CONTEXT_MONITOR_RESOURCE,
     CONTEXT_MONITOR_LINK_REMOTE,
     CONTEXT_MONITOR_MONITORING_LOCAL_REGISTEREDNAME,
+    CONTEXT_MONITOR_ALIAS,
+};
+
+enum ContextMonitorAliasType
+{
+    CONTEXT_MONITOR_ALIAS_EXPLICIT_UNALIAS,
+    CONTEXT_MONITOR_ALIAS_DEMONITOR,
 };
 
 #define UNLINK_ID_LINK_ACTIVE 0x0
@@ -207,6 +214,13 @@ struct MonitorLocalRegisteredNameMonitor
     term monitor_name;
 };
 
+struct MonitorAlias
+{
+    struct Monitor monitor;
+    uint64_t ref_ticks;
+    enum ContextMonitorAliasType alias_type;
+};
+
 // The other half is called ResourceMonitor and is a linked list of resources
 struct ResourceContextMonitor
 {
@@ -512,6 +526,8 @@ struct Monitor *monitor_link_new(term link_pid);
  */
 struct Monitor *monitor_new(term monitor_pid, uint64_t ref_ticks, bool is_monitoring);
 
+struct Monitor *monitor_alias_new(uint64_t ref_ticks, enum ContextMonitorAliasType alias_type);
+
 /**
  * @brief Create a monitor on a process by registered name.
  *
@@ -577,6 +593,9 @@ void context_unlink_ack(Context *ctx, term link_pid, uint64_t unlink_id);
  */
 void context_demonitor(Context *ctx, uint64_t ref_ticks);
 
+struct MonitorAlias *context_find_alias(Context *ctx, uint64_t ref_ticks);
+bool context_unalias(Context *ctx, uint64_t ref_ticks, bool from_demonitor);
+
 /**
  * @brief Get target of a monitor.
  *

src/libAtomVM/defaultatoms.def

@@ -209,3 +209,9 @@ X(LOAD_ATOM, "\x4", "load")
 X(JIT_X86_64_ATOM, "\xA", "jit_x86_64")
 X(JIT_AARCH64_ATOM, "\xB", "jit_aarch64")
 X(JIT_ARMV6M_ATOM, "\xA", "jit_armv6m")
+
+X(ALIAS_ATOM, "\x5", "alias")
+X(DEMONITOR_ATOM, "\x9", "demonitor")
+X(EXPLICIT_UNALIAS_ATOM, "\x10", "explicit_unalias")
+X(REPLY_DEMONITOR_ATOM, "\xF", "reply_demonitor")
+X(TAG_ATOM, "\x3", "tag")

src/libAtomVM/ets_hashtable.c

@@ -368,6 +368,9 @@ static uint32_t hash_term_incr(term t, int32_t h, GlobalContext *global)
         return hash_local_port(t, h, global);
     } else if (term_is_external_port(t)) {
         return hash_external_port(t, h, global);
+    } else if (term_is_pid_reference(t)) {
+        fprintf(stderr, "error: hash pid reference\n");
+        AVM_ABORT();
     } else if (term_is_local_reference(t)) {
         return hash_local_reference(t, h, global);
     } else if (term_is_external_reference(t)) {

src/libAtomVM/externalterm.c

@@ -483,6 +483,10 @@ static int serialize_term(uint8_t *buf, term t, GlobalContext *glb)
             WRITE_32_UNALIGNED(buf + k + 8, term_get_external_node_creation(t));
         }
         return k + 12;
+    } else if (term_is_pid_reference(t)) {
+        // FIXME: implement pid reference serialization
+        fprintf(stderr, "Error: serialize pid reference");
+        AVM_ABORT();
     } else if (term_is_local_reference(t)) {
         if (!IS_NULL_PTR(buf)) {
             buf[0] = NEWER_REFERENCE_EXT;