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

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The post operations (attach the found or new window to a context, update
the keep_always flag, and calculate the address) in three steps are
equivalent, and the two searching logics are quite simple.
Let's merge them to decrease the total lines.

No functional change, just refactoring.
This commit is contained in:
Yu Watanabe 2023-09-30 06:51:48 +09:00
parent 81598f5ead
commit 40f5e6a941
1 changed files with 41 additions and 112 deletions
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153
src/libsystemd/sd-journal/mmap-cache.c
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@ -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;
w = window_add(f, woffset, wsize, d);
if (!w) {
(void) munmap(d, wsize);
return -ENOMEM;
}
context_attach_window(f->cache, c, w);
*ret = (uint8_t*) w->ptr + (offset - w->offset);
return 1;
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) {