WebSVN – HelenOS – Diff – /trunk/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
+ * 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
  * for, the NS can leak memory because of the zombie tasks.
+}
 /** 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 (!hash_table_create(&phone_to_id, P2I_HASH_TABLE_CHAINS,
+, &p2i_ops)) {
+        printf(NAME ": No memory available for tasks\n");
+        return ENOMEM;
+    }
     if (event_subscribe(EVENT_WAIT, 0) != EOK)
         printf(NAME ": Error registering wait notifications\n");
     list_initialize(&pending_wait);
     ipcarg_t retval;
     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) {
+        retval = ENOENT;
+        goto out;
+    }
-    if ((ht == NULL) || (!ht->destroyed)) {
+    if (!ht->destroyed) {
         /* Add to pending list */
         pending_wait_t *pr =
             (pending_wait_t *) malloc(sizeof(pending_wait_t));
         if (!pr) {
             retval = ENOMEM;
 out:
     if (!(callid & IPC_CALLID_NOTIFICATION))
         ipc_answer_1(callid, retval, ht->retval);
+}
+int ns_task_id_intro(ipc_call_t *call)
+{
+    task_id_t id;
+    unsigned long keys[1];
+    link_t *link;
+    p2i_entry_t *e;
+    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;
+    link_initialize(&e->link);
+    e->phash = call->in_phone_hash;
+    e->id = id;
+    hash_table_insert(&phone_to_id, keys, &e->link);
+    return EOK;
+}
 int ns_task_retval(ipc_call_t *call)
+{
     task_id_t id;
     unsigned long keys[2];
+    int rc;
-    id = MERGE_LOUP32(IPC_GET_ARG1(*call), IPC_GET_ARG2(*call));
+    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);
         hash_table_get_instance(link, hashed_task_t, link) : NULL;
     if ((ht == NULL) || ht->destroyed)
         return EINVAL;
-    ht->retval = IPC_GET_ARG3(*call);
+    ht->retval = IPC_GET_ARG1(*call);
+    return EOK;
+}
+int ns_task_disconnect(ipc_call_t *call)
+{
+    unsigned long keys[1];
+    keys[0] = call->in_phone_hash;
+    hash_table_remove(&phone_to_id, keys, 1);
+    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)/trunk/uspace/srv/ns/task.c – Rev 4617 → 4618