WebSVN – HelenOS – Diff – /branches/dd/uspace/srv/ns/task.c

 /*
  * Copyright (c) 2009 Martin Decky
+ * Copyright (c) 2009 Jiri Svoboda
  * All rights reserved.
+ *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
 #include <macros.h>
 #include "task.h"
 #include "ns.h"
 #define TASK_HASH_TABLE_CHAINS  256
+#define P2I_HASH_TABLE_CHAINS  256
+static int get_id_by_phone(ipcarg_t phone_hash, task_id_t *id);
 /* TODO:
+ *
- * The current implementation of waiting on a task is not perfect. If somebody
- * wants to wait on a task which has already finished before the NS asked
- * the kernel to receive notifications, it would block indefinitively.
- *
- * A solution to this is to fail immediately on a task for which no creation
- * notification was received yet. However, there is a danger of a race condition
- * in this solution -- the caller has to make sure that it is not trying to wait
- * before the NS has a change to receive the task creation notification. This
- * can be assured by waiting for this event in task_spawn().
- *
- * Finally, as there is currently no convention that each task has to be waited
+ * As there is currently no convention that each task has to be waited
  * for, the NS can leak memory because of the zombie tasks.
+ *
  */
 /** Task hash table item. */
 typedef struct {
     link_t link;
-    task_id_t id;    /**< Task ID. */
+    task_id_t id;   /**< Task ID. */
-    bool destroyed;
+    bool finished;  /**< Task is done. */
+    bool have_rval; /**< Task returned a value. */
+    int retval; /**< The return value. */
 } hashed_task_t;
 /** Compute hash index into task hash table.
+ *
  * @param key Pointer keys. However, only the first key (i.e. truncated task
+}
 /** Compare a key with hashed item.
+ *
  * @param key  Array of keys.
- * @param keys Must be lesser or equal to 2.
+ * @param keys Must be less than or equal to 2.
  * @param item Pointer to a hash table item.
+ *
  * @return Non-zero if the key matches the item, zero otherwise.
+ *
  */
 };
 /** Task hash table structure. */
 static hash_table_t task_hash_table;
+typedef struct {
+    link_t link;
+    ipcarg_t phash;    /**< Task ID. */
+    task_id_t id;    /**< Task ID. */
+} p2i_entry_t;
+/** Compute hash index into task hash table.
+ *
+ * @param key Array of keys.
+ * @return Hash index corresponding to key[0].
+ *
+ */
+static hash_index_t p2i_hash(unsigned long *key)
+{
+    assert(key);
+    return (*key % TASK_HASH_TABLE_CHAINS);
+}
+/** Compare a key with hashed item.
+ *
+ * @param key  Array of keys.
+ * @param keys Must be less than or equal to 1.
+ * @param item Pointer to a hash table item.
+ *
+ * @return Non-zero if the key matches the item, zero otherwise.
+ *
+ */
+static int p2i_compare(unsigned long key[], hash_count_t keys, link_t *item)
+{
+    assert(key);
+    assert(keys == 1);
+    assert(item);
+    p2i_entry_t *e = hash_table_get_instance(item, p2i_entry_t, link);
+    return (key[0] == e->phash);
+}
+/** Perform actions after removal of item from the hash table.
+ *
+ * @param item Item that was removed from the hash table.
+ *
+ */
+static void p2i_remove(link_t *item)
+{
+    assert(item);
+    free(hash_table_get_instance(item, p2i_entry_t, link));
+}
+/** Operations for task hash table. */
+static hash_table_operations_t p2i_ops = {
+    .hash = p2i_hash,
+    .compare = p2i_compare,
+    .remove_callback = p2i_remove
+};
+/** Map phone hash to task ID */
+static hash_table_t phone_to_id;
 /** Pending task wait structure. */
 typedef struct {
     link_t link;
     task_id_t id;         /**< Task ID. */
     ipc_callid_t callid;  /**< Call ID waiting for the connection */
     if (!hash_table_create(&task_hash_table, TASK_HASH_TABLE_CHAINS,
 , &task_hash_table_ops)) {
         printf(NAME ": No memory available for tasks\n");
         return ENOMEM;
+    }
-    if (event_subscribe(EVENT_WAIT, 0) != EOK)
+    if (!hash_table_create(&phone_to_id, P2I_HASH_TABLE_CHAINS,
+, &p2i_ops)) {
-        printf(NAME ": Error registering wait notifications\n");
+        printf(NAME ": No memory available for tasks\n");
+        return ENOMEM;
+    }
     list_initialize(&pending_wait);
     return EOK;
+}
 /** Process pending wait requests */
 void process_pending_wait(void)
+{
     link_t *cur;
+    task_exit_t texit;
 loop:
     for (cur = pending_wait.next; cur != &pending_wait; cur = cur->next) {
         pending_wait_t *pr = list_get_instance(cur, pending_wait_t, link);
         link_t *link = hash_table_find(&task_hash_table, keys);
         if (!link)
             continue;
         hashed_task_t *ht = hash_table_get_instance(link, hashed_task_t, link);
-        if (!ht->destroyed)
+        if (!ht->finished)
             continue;
-        if (!(pr->callid & IPC_CALLID_NOTIFICATION))
+        if (!(pr->callid & IPC_CALLID_NOTIFICATION)) {
+            texit = ht->have_rval ? TASK_EXIT_NORMAL :
+                TASK_EXIT_UNEXPECTED;
-            ipc_answer_0(pr->callid, EOK);
+            ipc_answer_2(pr->callid, EOK, texit,
+                ht->retval);
+        }
         hash_table_remove(&task_hash_table, keys, 2);
         list_remove(cur);
         free(pr);
         goto loop;
+    }
+}
-static void fail_pending_wait(task_id_t id, int rc)
-{
-    link_t *cur;
-loop:
-    for (cur = pending_wait.next; cur != &pending_wait; cur = cur->next) {
-        pending_wait_t *pr = list_get_instance(cur, pending_wait_t, link);
-        if (pr->id == id) {
-            if (!(pr->callid & IPC_CALLID_NOTIFICATION))
-                ipc_answer_0(pr->callid, rc);
-            list_remove(cur);
-            free(pr);
-            goto loop;
-        }
-    }
-}
-void wait_notification(wait_type_t et, task_id_t id)
-{
-    unsigned long keys[2] = {
-        LOWER32(id),
-        UPPER32(id)
-    };
-    link_t *link = hash_table_find(&task_hash_table, keys);
-    if (link == NULL) {
-        hashed_task_t *ht =
-            (hashed_task_t *) malloc(sizeof(hashed_task_t));
-        if (ht == NULL) {
-            fail_pending_wait(id, ENOMEM);
-            return;
-        }
-        link_initialize(&ht->link);
-        ht->id = id;
-        ht->destroyed = (et == TASK_CREATE) ? false : true;
-        hash_table_insert(&task_hash_table, keys, &ht->link);
-    } else {
-        hashed_task_t *ht =
-            hash_table_get_instance(link, hashed_task_t, link);
-        ht->destroyed = (et == TASK_CREATE) ? false : true;
-    }
-}
 void wait_for_task(task_id_t id, ipc_call_t *call, ipc_callid_t callid)
+{
     ipcarg_t retval;
+    task_exit_t texit;
     unsigned long keys[2] = {
         LOWER32(id),
         UPPER32(id)
     };
     link_t *link = hash_table_find(&task_hash_table, keys);
     hashed_task_t *ht = (link != NULL) ?
         hash_table_get_instance(link, hashed_task_t, link) : NULL;
+    if (ht == NULL) {
+        /* No such task exists. */
+        retval = ENOENT;
+        goto out;
+    }
-    if ((ht == NULL) || (!ht->destroyed)) {
+    if (!ht->finished) {
         /* Add to pending list */
         pending_wait_t *pr =
             (pending_wait_t *) malloc(sizeof(pending_wait_t));
         if (!pr) {
             retval = ENOMEM;
     hash_table_remove(&task_hash_table, keys, 2);
     retval = EOK;
 out:
-    if (!(callid & IPC_CALLID_NOTIFICATION))
+    if (!(callid & IPC_CALLID_NOTIFICATION)) {
+        texit = ht->have_rval ? TASK_EXIT_NORMAL : TASK_EXIT_UNEXPECTED;
-        ipc_answer_0(callid, retval);
+        ipc_answer_2(callid, retval, texit, ht->retval);
+    }
+}
+int ns_task_id_intro(ipc_call_t *call)
+{
+    task_id_t id;
+    unsigned long keys[2];
+    link_t *link;
+    p2i_entry_t *e;
+    hashed_task_t *ht;
+    id = MERGE_LOUP32(IPC_GET_ARG1(*call), IPC_GET_ARG2(*call));
+    keys[0] = call->in_phone_hash;
+    link = hash_table_find(&phone_to_id, keys);
+    if (link != NULL)
+        return EEXISTS;
+    e = (p2i_entry_t *) malloc(sizeof(p2i_entry_t));
+    if (e == NULL)
+        return ENOMEM;
+    ht = (hashed_task_t *) malloc(sizeof(hashed_task_t));
+    if (ht == NULL)
+        return ENOMEM;
+    /* Insert to phone-to-id map. */
+    link_initialize(&e->link);
+    e->phash = call->in_phone_hash;
+    e->id = id;
+    hash_table_insert(&phone_to_id, keys, &e->link);
+    /* Insert to main table. */
+    keys[0] = LOWER32(id);
+    keys[1] = UPPER32(id);
+    link_initialize(&ht->link);
+    ht->id = id;
+    ht->finished = false;
+    ht->have_rval = false;
+    ht->retval = -1;
+    hash_table_insert(&task_hash_table, keys, &ht->link);
+    return EOK;
+}
+int ns_task_retval(ipc_call_t *call)
+{
+    task_id_t id;
+    unsigned long keys[2];
+    int rc;
+    rc = get_id_by_phone(call->in_phone_hash, &id);
+    if (rc != EOK)
+        return rc;
+    keys[0] = LOWER32(id);
+    keys[1] = UPPER32(id);
+    link_t *link = hash_table_find(&task_hash_table, keys);
+    hashed_task_t *ht = (link != NULL) ?
+        hash_table_get_instance(link, hashed_task_t, link) : NULL;
+    if ((ht == NULL) || ht->finished)
+        return EINVAL;
+    ht->finished = true;
+    ht->have_rval = true;
+    ht->retval = IPC_GET_ARG1(*call);
+    return EOK;
+}
+int ns_task_disconnect(ipc_call_t *call)
+{
+    unsigned long keys[2];
+    task_id_t id;
+    int rc;
+    rc = get_id_by_phone(call->in_phone_hash, &id);
+    if (rc != EOK)
+        return rc;
+    /* Delete from phone-to-id map. */
+    keys[0] = call->in_phone_hash;
+    hash_table_remove(&phone_to_id, keys, 1);
+    /* Mark task as finished. */
+    keys[0] = LOWER32(id);
+    keys[1] = UPPER32(id);
+    link_t *link = hash_table_find(&task_hash_table, keys);
+    hashed_task_t *ht =
+        hash_table_get_instance(link, hashed_task_t, link);
+    if (ht == NULL)
+        return EOK;
+    ht->finished = true;
+    return EOK;
+}
+static int get_id_by_phone(ipcarg_t phone_hash, task_id_t *id)
+{
+    unsigned long keys[1];
+    link_t *link;
+    p2i_entry_t *e;
+    keys[0] = phone_hash;
+    link = hash_table_find(&phone_to_id, keys);
+    if (link == NULL)
+        return ENOENT;
+    e = hash_table_get_instance(link, p2i_entry_t, link);
+    *id = e->id;
+    return EOK;
+}
 /**
  * @}
  */

Subversion Repositories HelenOS

(root)/branches/dd/uspace/srv/ns/task.c @ 4676 – Rev 4537 → 4668