mmap-cache: merge mmap_cache_fd_get() with try_context() and find_mmap()

[thirdparty/systemd.git] / src / libsystemd / sd-journal / mmap-cache.c

diff --git a/src/libsystemd/sd-journal/mmap-cache.c b/src/libsystemd/sd-journal/mmap-cache.c
index 11b1abd8b7f388790bd83ae4ff7f7a945a049a23..fc80862021a4a44bbfc2179c352fedca1d04f3f5 100644 (file)
--- a/src/libsystemd/sd-journal/mmap-cache.c
+++ b/src/libsystemd/sd-journal/mmap-cache.c
@@ -147,14 +147,11 @@ static bool window_matches(Window *w, MMapFileDescriptor *f, uint64_t offset, si
                 offset + size <= w->offset + w->size;
 }
 
-static Window *window_add(MMapCache *m, MMapFileDescriptor *f, bool keep_always, uint64_t offset, size_t size, void *ptr) {
+static Window* window_add(MMapFileDescriptor *f, uint64_t offset, size_t size, void *ptr) {
+        MMapCache *m = mmap_cache_fd_cache(f);
         Window *w;
 
-        assert(m);
-        assert(f);
-
         if (!m->last_unused || m->n_windows <= WINDOWS_MIN) {
-
                 /* Allocate a new window */
                 w = new(Window, 1);
                 if (!w)
@@ -167,15 +164,12 @@ static Window *window_add(MMapCache *m, MMapFileDescriptor *f, bool keep_always,
         *w = (Window) {
                 .cache = m,
                 .fd = f,
-                .keep_always = keep_always,
                 .offset = offset,
                 .size = size,
                 .ptr = ptr,
         };
 
-        LIST_PREPEND(by_fd, f->windows, w);
-
-        return w;
+        return LIST_PREPEND(by_fd, f->windows, w);
 }
 
 static void context_detach_window(MMapCache *m, Context *c) {
@@ -246,79 +240,6 @@ static MMapCache* mmap_cache_free(MMapCache *m) {
 
 DEFINE_TRIVIAL_REF_UNREF_FUNC(MMapCache, mmap_cache, mmap_cache_free);
 
-static int try_context(
-                MMapFileDescriptor *f,
-                Context *c,
-                bool keep_always,
-                uint64_t offset,
-                size_t size,
-                void **ret) {
-
-        assert(f);
-        assert(f->cache);
-        assert(f->cache->n_ref > 0);
-        assert(c);
-        assert(size > 0);
-        assert(ret);
-
-        if (!c->window)
-                return 0;
-
-        if (!window_matches(c->window, f, offset, size)) {
-
-                /* Drop the reference to the window, since it's unnecessary now */
-                context_detach_window(f->cache, c);
-                return 0;
-        }
-
-        if (c->window->fd->sigbus)
-                return -EIO;
-
-        c->window->keep_always = c->window->keep_always || keep_always;
-
-        *ret = (uint8_t*) c->window->ptr + (offset - c->window->offset);
-        f->cache->n_context_cache_hit++;
-
-        return 1;
-}
-
-static int find_mmap(
-                MMapFileDescriptor *f,
-                Context *c,
-                bool keep_always,
-                uint64_t offset,
-                size_t size,
-                void **ret) {
-
-        Window *found = NULL;
-
-        assert(f);
-        assert(f->cache);
-        assert(f->cache->n_ref > 0);
-        assert(c);
-        assert(size > 0);
-
-        if (f->sigbus)
-                return -EIO;
-
-        LIST_FOREACH(by_fd, w, f->windows)
-                if (window_matches(w, f, offset, size)) {
-                        found = w;
-                        break;
-                }
-
-        if (!found)
-                return 0;
-
-        context_attach_window(f->cache, c, found);
-        found->keep_always = found->keep_always || keep_always;
-
-        *ret = (uint8_t*) found->ptr + (offset - found->offset);
-        f->cache->n_window_list_hit++;
-
-        return 1;
-}
-
 static int mmap_try_harder(MMapFileDescriptor *f, void *addr, int flags, uint64_t offset, size_t size, void **ret) {
         MMapCache *m = mmap_cache_fd_cache(f);
 
@@ -346,12 +267,10 @@ static int mmap_try_harder(MMapFileDescriptor *f, void *addr, int flags, uint64_
 
 static int add_mmap(
                 MMapFileDescriptor *f,
-                Context *c,
-                bool keep_always,
                 uint64_t offset,
                 size_t size,
                 struct stat *st,
-                void **ret) {
+                Window **ret) {
 
         uint64_t woffset, wsize;
         Window *w;
@@ -359,9 +278,6 @@ static int add_mmap(
         int r;
 
         assert(f);
-        assert(f->cache);
-        assert(f->cache->n_ref > 0);
-        assert(c);
         assert(size > 0);
         assert(ret);
 
@@ -397,19 +313,14 @@ static int add_mmap(
         if (r < 0)
                 return r;
 
-        w = window_add(f->cache, f, keep_always, woffset, wsize, d);
-        if (!w)
-                goto outofmem;
-
-        context_attach_window(f->cache, c, w);
-
-        *ret = (uint8_t*) w->ptr + (offset - w->offset);
-
-        return 1;
+        w = window_add(f, woffset, wsize, d);
+        if (!w) {
+                (void) munmap(d, wsize);
+                return -ENOMEM;
+        }
 
-outofmem:
-        (void) munmap(d, wsize);
-        return -ENOMEM;
+        *ret = w;
+        return 0;
 }
 
 int mmap_cache_fd_get(
@@ -421,32 +332,50 @@ int mmap_cache_fd_get(
                 struct stat *st,
                 void **ret) {
 
+        MMapCache *m = mmap_cache_fd_cache(f);
         Context *c;
+        Window *w;
         int r;
 
-        assert(f);
-        assert(f->cache);
-        assert(f->cache->n_ref > 0);
+        assert(context < MMAP_CACHE_MAX_CONTEXTS);
         assert(size > 0);
         assert(ret);
-        assert(context < MMAP_CACHE_MAX_CONTEXTS);
+
+        if (f->sigbus)
+                return -EIO;
 
         c = &f->cache->contexts[context];
 
         /* Check whether the current context is the right one already */
-        r = try_context(f, c, keep_always, offset, size, ret);
-        if (r != 0)
-                return r;
+        if (window_matches(c->window, f, offset, size)) {
+                m->n_context_cache_hit++;
+                w = c->window;
+                goto found;
+        }
+
+        /* Drop the reference to the window, since it's unnecessary now */
+        context_detach_window(m, c);
 
         /* Search for a matching mmap */
-        r = find_mmap(f, c, keep_always, offset, size, ret);
-        if (r != 0)
-                return r;
+        LIST_FOREACH(by_fd, i, f->windows)
+                if (window_matches(i, f, offset, size)) {
+                        m->n_window_list_hit++;
+                        w = i;
+                        goto found;
+                }
 
-        f->cache->n_missed++;
+        m->n_missed++;
 
         /* Create a new mmap */
-        return add_mmap(f, c, keep_always, offset, size, st, ret);
+        r = add_mmap(f, offset, size, st, &w);
+        if (r < 0)
+                return r;
+
+found:
+        w->keep_always = w->keep_always || keep_always;
+        context_attach_window(m, c, w);
+        *ret = (uint8_t*) w->ptr + (offset - w->offset);
+        return 0;
 }
 
 void mmap_cache_stats_log_debug(MMapCache *m) {