1 /* Blue Sky: File Systems in the Cloud
3 * Copyright (C) 2009 The Regents of the University of California
4 * Written by Michael Vrable <mvrable@cs.ucsd.edu>
15 #include "bluesky-private.h"
17 /* Miscellaneous useful functions that don't really fit anywhere else. */
19 bluesky_time_hires bluesky_now_hires()
23 if (clock_gettime(CLOCK_REALTIME, &time) != 0) {
24 perror("clock_gettime");
28 return (int64_t)(time.tv_sec) * 1000000000 + time.tv_nsec;
31 /* Convert a UTF-8 string to lowercase. This can be used to implement
32 * case-insensitive lookups and comparisons, by normalizing all values to
33 * lowercase first. Returns a newly-allocated string as a result. */
34 gchar *bluesky_lowercase(const gchar *s)
36 /* TODO: Unicode handling; for now just do ASCII. */
37 return g_ascii_strdown(s, -1);
40 gboolean bluesky_inode_is_ready(BlueSkyInode *inode)
45 g_mutex_lock(inode->lock);
46 gboolean valid = (inode->type != BLUESKY_PENDING
47 && inode->type != BLUESKY_INVALID);
49 g_mutex_unlock(inode->lock);
54 /**** Reference-counted strings. ****/
56 /* Create and return a new reference-counted string. The reference count is
57 * initially one. The newly-returned string takes ownership of the memory
58 * pointed at by data, and will call g_free on it when the reference count
60 BlueSkyRCStr *bluesky_string_new(gpointer data, gsize len)
62 BlueSkyRCStr *string = g_new(BlueSkyRCStr, 1);
66 g_atomic_int_set(&string->refcount, 1);
70 /* Create a new BlueSkyRCStr from a GString. The GString is destroyed. */
71 BlueSkyRCStr *bluesky_string_new_from_gstring(GString *s)
74 return bluesky_string_new(g_string_free(s, FALSE), len);
77 /* Create a new BlueSkyRCStr from a memory-mapped buffer. */
78 BlueSkyRCStr *bluesky_string_new_from_mmap(BlueSkyMmap *mmap,
79 int offset, gsize len)
81 g_assert(offset + len < mmap->len);
83 BlueSkyRCStr *string = g_new(BlueSkyRCStr, 1);
85 g_atomic_int_inc(&mmap->refcount);
86 string->data = (char *)mmap->addr + offset;
88 g_atomic_int_set(&string->refcount, 1);
92 void bluesky_string_ref(BlueSkyRCStr *string)
97 g_atomic_int_inc(&string->refcount);
100 void bluesky_string_unref(BlueSkyRCStr *string)
105 if (g_atomic_int_dec_and_test(&string->refcount)) {
106 if (string->mmap == NULL) {
107 g_free(string->data);
109 bluesky_mmap_unref(string->mmap);
115 /* Duplicate and return a new reference-counted string, containing a copy of
116 * the original data, with a reference count of 1. As an optimization, if the
117 * passed-in string already has a reference count of 1, the original is
118 * returned. Can be used to make a mutable copy of a shared string. For this
119 * to truly be safe, it is probably needed that there be some type of lock
120 * protecting access to the string. */
121 BlueSkyRCStr *bluesky_string_dup(BlueSkyRCStr *string)
126 if (string->mmap != NULL) {
128 s = bluesky_string_new(g_memdup(string->data, string->len),
130 bluesky_string_unref(string);
134 if (g_atomic_int_dec_and_test(&string->refcount)) {
135 /* There are no other shared copies, so return this one. */
136 g_atomic_int_inc(&string->refcount);
139 return bluesky_string_new(g_memdup(string->data, string->len),
144 /* Resize the data block used by a BlueSkyRCStr. The data pointer might change
145 * after making this call, so it should not be cached across calls to this
146 * function. To avoid confusing any other users, the caller probably ought to
147 * hold the only reference to the string (by calling bluesky_string_dup first
149 void bluesky_string_resize(BlueSkyRCStr *string, gsize len)
151 g_assert(string->mmap == NULL);
153 if (string->len == len)
156 g_warn_if_fail(string->refcount == 1);
158 string->data = g_realloc(string->data, len);
162 /* Cache LRU list management functions. These manage the doubly-linked list of
163 * inodes sorted by accessed/modified time. The FS lock should be held while
166 * _remove will unlink an inode from the linked list.
168 * _prepend and _append insert an inode at the head or tail of the linked list,
169 * and return a pointer to the linked list element (which should be stored in
170 * the inode); the inode should not already be in the list.
172 * _head and _tail simply return the first or last item inode in the list. */
173 void bluesky_list_unlink(GList *head, GList *item)
178 if (head->prev == item)
179 head->prev = item->prev;
180 head->next = g_list_delete_link(head->next, item);
183 GList *bluesky_list_prepend(GList *head, BlueSkyInode *inode)
185 head->next = g_list_prepend(head->next, inode);
186 if (head->prev == NULL)
187 head->prev = g_list_last(head->next);
191 GList *bluesky_list_append(GList *head, BlueSkyInode *inode)
193 if (head->next == NULL)
194 return bluesky_list_prepend(head, inode);
196 g_assert(head->prev != NULL && head->prev->next == NULL);
198 GList *link = g_list_alloc();
201 link->prev = head->prev;
202 head->prev->next = link;
207 BlueSkyInode *bluesky_list_head(GList *head)
209 if (head->next == NULL)
212 return (BlueSkyInode *)head->next->data;
215 BlueSkyInode *bluesky_list_tail(GList *head)
217 if (head->prev == NULL)
220 return (BlueSkyInode *)head->prev->data;