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=6c9194a1a5faa9ca24161f1a8d34d747e176f1e7;hb=06cc69d44c8ff2b652527357f28acd4cbe77c814;hpb=71fda00f320379f5cbee8e118848de98caaa229d diff --git a/src/journal/mmap-cache.c b/src/journal/mmap-cache.c index 6c9194a1a..b7db6f1da 100644 --- a/src/journal/mmap-cache.c +++ b/src/journal/mmap-cache.c @@ -38,7 +38,7 @@ typedef struct FileDescriptor FileDescriptor; struct Window { MMapCache *cache; - bool keep_always; + unsigned keep_always; bool in_unused; int prot; @@ -72,6 +72,9 @@ struct MMapCache { int n_ref; unsigned n_windows; + unsigned n_hit, n_missed; + + Hashmap *fds; Hashmap *contexts; @@ -182,7 +185,7 @@ static void context_detach_window(Context *c) { c->window = NULL; 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(unused, c->cache->unused, w); if (!c->cache->last_unused) @@ -224,7 +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; @@ -278,7 +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; @@ -349,7 +352,8 @@ static int try_context( bool keep_always, uint64_t offset, size_t size, - void **ret) { + void **ret, + void **release_cookie) { Context *c; @@ -357,7 +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) @@ -375,9 +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; } @@ -389,7 +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; @@ -399,7 +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) @@ -419,9 +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; } @@ -434,7 +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; @@ -447,7 +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); @@ -494,15 +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; @@ -517,8 +526,15 @@ static int add_mmap( c->window = w; 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( @@ -530,7 +546,8 @@ int mmap_cache_get( uint64_t offset, size_t size, struct stat *st, - void **ret) { + void **ret, + void **release_cookie) { int r; @@ -538,20 +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) { @@ -578,3 +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; +}