X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=src%2Fjournal%2Fmmap-cache.c;h=b7db6f1da5c2c7ffbc10c00215e783891304fb24;hp=54bf1148e18d572d67db3d980a8609b7325971b7;hb=9833a66c7eba011c3740867c80133bc6fa976aa3;hpb=44a6b1b68029833893f6e9cee35aa27a974038f6

diff --git a/src/journal/mmap-cache.c b/src/journal/mmap-cache.c
index 54bf1148e..b7db6f1da 100644
--- a/src/journal/mmap-cache.c
+++ b/src/journal/mmap-cache.c
@@ -38,12 +38,12 @@ typedef struct FileDescriptor FileDescriptor;
 struct Window {
         MMapCache *cache;
 
-        bool keep_always;
+        unsigned keep_always;
         bool in_unused;
 
+        int prot;
         void *ptr;
         uint64_t offset;
-        int prot;
         size_t size;
 
         FileDescriptor *fd;
@@ -70,12 +70,14 @@ struct FileDescriptor {
 
 struct MMapCache {
         int n_ref;
+        unsigned n_windows;
+
+        unsigned n_hit, n_missed;
+
 
         Hashmap *fds;
         Hashmap *contexts;
 
-        unsigned n_windows;
-
         LIST_HEAD(Window, unused);
         Window *last_unused;
 };
@@ -111,13 +113,13 @@ static void window_unlink(Window *w) {
                 munmap(w->ptr, w->size);
 
         if (w->fd)
-                LIST_REMOVE(Window, by_fd, w->fd->windows, w);
+                LIST_REMOVE(by_fd, w->fd->windows, w);
 
         if (w->in_unused) {
                 if (w->cache->last_unused == w)
                         w->cache->last_unused = w->unused_prev;
 
-                LIST_REMOVE(Window, unused, w->cache->unused, w);
+                LIST_REMOVE(unused, w->cache->unused, w);
         }
 
         LIST_FOREACH(by_window, c, w->contexts) {
@@ -181,11 +183,11 @@ static void context_detach_window(Context *c) {
 
         w = c->window;
         c->window = NULL;
-        LIST_REMOVE(Context, by_window, w->contexts, c);
+        LIST_REMOVE(by_window, w->contexts, c);
 
-        if (!w->contexts && !w->keep_always) {
+        if (!w->contexts && w->keep_always == 0) {
                 /* Not used anymore? */
-                LIST_PREPEND(Window, unused, c->cache->unused, w);
+                LIST_PREPEND(unused, c->cache->unused, w);
                 if (!c->cache->last_unused)
                         c->cache->last_unused = w;
 
@@ -204,7 +206,7 @@ static void context_attach_window(Context *c, Window *w) {
 
         if (w->in_unused) {
                 /* Used again? */
-                LIST_REMOVE(Window, unused, c->cache->unused, w);
+                LIST_REMOVE(unused, c->cache->unused, w);
                 if (c->cache->last_unused == w)
                         c->cache->last_unused = w->unused_prev;
 
@@ -212,7 +214,7 @@ static void context_attach_window(Context *c, Window *w) {
         }
 
         c->window = w;
-        LIST_PREPEND(Context, by_window, w->contexts, c);
+        LIST_PREPEND(by_window, w->contexts, c);
 }
 
 static Context *context_add(MMapCache *m, unsigned id) {
@@ -225,7 +227,7 @@ static Context *context_add(MMapCache *m, unsigned id) {
         if (c)
                 return c;
 
-        r = hashmap_ensure_allocated(&m->contexts, trivial_hash_func, trivial_compare_func);
+        r = hashmap_ensure_allocated(&m->contexts, NULL);
         if (r < 0)
                 return NULL;
 
@@ -279,7 +281,7 @@ static FileDescriptor* fd_add(MMapCache *m, int fd) {
         if (f)
                 return f;
 
-        r = hashmap_ensure_allocated(&m->fds, trivial_hash_func, trivial_compare_func);
+        r = hashmap_ensure_allocated(&m->fds, NULL);
         if (r < 0)
                 return NULL;
 
@@ -308,9 +310,13 @@ static void mmap_cache_free(MMapCache *m) {
         while ((c = hashmap_first(m->contexts)))
                 context_free(c);
 
+        hashmap_free(m->contexts);
+
         while ((f = hashmap_first(m->fds)))
                 fd_free(f);
 
+        hashmap_free(m->fds);
+
         while (m->unused)
                 window_free(m->unused);
 
@@ -346,7 +352,8 @@ static int try_context(
                 bool keep_always,
                 uint64_t offset,
                 size_t size,
-                void **ret) {
+                void **ret,
+                void **release_cookie) {
 
         Context *c;
 
@@ -354,7 +361,6 @@ static int try_context(
         assert(m->n_ref > 0);
         assert(fd >= 0);
         assert(size > 0);
-        assert(ret);
 
         c = hashmap_get(m->contexts, UINT_TO_PTR(context+1));
         if (!c)
@@ -372,9 +378,12 @@ static int try_context(
                 return 0;
         }
 
-        c->window->keep_always = c->window->keep_always || keep_always;
+        c->window->keep_always += keep_always;
 
-        *ret = (uint8_t*) c->window->ptr + (offset - c->window->offset);
+        if (ret)
+                *ret = (uint8_t*) c->window->ptr + (offset - c->window->offset);
+        if (keep_always && release_cookie)
+                *release_cookie = c->window;
         return 1;
 }
 
@@ -386,7 +395,8 @@ static int find_mmap(
                 bool keep_always,
                 uint64_t offset,
                 size_t size,
-                void **ret) {
+                void **ret,
+                void **release_cookie) {
 
         FileDescriptor *f;
         Window *w;
@@ -396,7 +406,6 @@ static int find_mmap(
         assert(m->n_ref > 0);
         assert(fd >= 0);
         assert(size > 0);
-        assert(ret);
 
         f = hashmap_get(m->fds, INT_TO_PTR(fd + 1));
         if (!f)
@@ -416,9 +425,12 @@ static int find_mmap(
                 return -ENOMEM;
 
         context_attach_window(c, w);
-        w->keep_always = w->keep_always || keep_always;
+        w->keep_always += keep_always;
 
-        *ret = (uint8_t*) w->ptr + (offset - w->offset);
+        if (ret)
+                *ret = (uint8_t*) w->ptr + (offset - w->offset);
+        if (keep_always && release_cookie)
+                *release_cookie = c->window;
         return 1;
 }
 
@@ -431,7 +443,8 @@ static int add_mmap(
                 uint64_t offset,
                 size_t size,
                 struct stat *st,
-                void **ret) {
+                void **ret,
+                void **release_cookie) {
 
         uint64_t woffset, wsize;
         Context *c;
@@ -444,7 +457,6 @@ static int add_mmap(
         assert(m->n_ref > 0);
         assert(fd >= 0);
         assert(size > 0);
-        assert(ret);
 
         woffset = offset & ~((uint64_t) page_size() - 1ULL);
         wsize = size + (offset - woffset);
@@ -491,15 +503,15 @@ static int add_mmap(
 
         c = context_add(m, context);
         if (!c)
-                return -ENOMEM;
+                goto outofmem;
 
         f = fd_add(m, fd);
         if (!f)
-                return -ENOMEM;
+                goto outofmem;
 
         w = window_add(m);
         if (!w)
-                return -ENOMEM;
+                goto outofmem;
 
         w->keep_always = keep_always;
         w->ptr = d;
@@ -508,14 +520,21 @@ static int add_mmap(
         w->size = wsize;
         w->fd = f;
 
-        LIST_PREPEND(Window, by_fd, f->windows, w);
+        LIST_PREPEND(by_fd, f->windows, w);
 
         context_detach_window(c);
         c->window = w;
-        LIST_PREPEND(Context, by_window, w->contexts, c);
+        LIST_PREPEND(by_window, w->contexts, c);
 
-        *ret = (uint8_t*) w->ptr + (offset - w->offset);
+        if (ret)
+                *ret = (uint8_t*) w->ptr + (offset - w->offset);
+        if (keep_always && release_cookie)
+                *release_cookie = c->window;
         return 1;
+
+outofmem:
+        munmap(d, wsize);
+        return -ENOMEM;
 }
 
 int mmap_cache_get(
@@ -527,7 +546,8 @@ int mmap_cache_get(
                 uint64_t offset,
                 size_t size,
                 struct stat *st,
-                void **ret) {
+                void **ret,
+                void **release_cookie) {
 
         int r;
 
@@ -535,20 +555,57 @@ int mmap_cache_get(
         assert(m->n_ref > 0);
         assert(fd >= 0);
         assert(size > 0);
-        assert(ret);
 
         /* Check whether the current context is the right one already */
-        r = try_context(m, fd, prot, context, keep_always, offset, size, ret);
-        if (r != 0)
+        r = try_context(m, fd, prot, context, keep_always, offset, size, ret, release_cookie);
+        if (r != 0) {
+                m->n_hit ++;
                 return r;
+        }
 
         /* Search for a matching mmap */
-        r = find_mmap(m, fd, prot, context, keep_always, offset, size, ret);
-        if (r != 0)
+        r = find_mmap(m, fd, prot, context, keep_always, offset, size, ret, release_cookie);
+        if (r != 0) {
+                m->n_hit ++;
                 return r;
+        }
+
+        m->n_missed++;
 
         /* Create a new mmap */
-        return add_mmap(m, fd, prot, context, keep_always, offset, size, st, ret);
+        return add_mmap(m, fd, prot, context, keep_always, offset, size, st, ret, release_cookie);
+}
+
+int mmap_cache_release(
+                MMapCache *m,
+                int fd,
+                void *release_cookie) {
+
+        FileDescriptor *f;
+        Window *w;
+
+        assert(m);
+        assert(m->n_ref > 0);
+        assert(fd >= 0);
+
+        f = hashmap_get(m->fds, INT_TO_PTR(fd + 1));
+        if (!f)
+                return -EBADF;
+
+        assert(f->fd == fd);
+
+        LIST_FOREACH(by_fd, w, f->windows)
+                if (w == release_cookie)
+                        break;
+
+        if (!w)
+                return -ENOENT;
+
+        if (w->keep_always == 0)
+                return -ENOLCK;
+
+        w->keep_always -= 1;
+        return 0;
 }
 
 void mmap_cache_close_fd(MMapCache *m, int fd) {
@@ -575,3 +632,15 @@ void mmap_cache_close_context(MMapCache *m, unsigned context) {
 
         context_free(c);
 }
+
+unsigned mmap_cache_get_hit(MMapCache *m) {
+        assert(m);
+
+        return m->n_hit;
+}
+
+unsigned mmap_cache_get_missed(MMapCache *m) {
+        assert(m);
+
+        return m->n_missed;
+}