Fork of Original Code Base: anongit.freedesktop.org/systemd

This is the initial fork of the code base from freedsktop.org.
The code is provided here as a reference of the initial starting
point and for possible future checkouts after a large portion
of this code is removed.

Merge git://anongit.freedesktop.org/systemd/systemd

1 files changed, 577 insertions, 0 deletions

diff --git a/src/journal/mmap-cache.c b/src/journal/mmap-cache.c
new file mode 100644
index 0000000000..251aefe121
--- /dev/null
+++ b/src/journal/mmap-cache.c
@@ -0,0 +1,577 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2012 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <errno.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <string.h>
+
+#include "hashmap.h"
+#include "list.h"
+#include "log.h"
+#include "util.h"
+#include "macro.h"
+#include "mmap-cache.h"
+
+typedef struct Window Window;
+typedef struct Context Context;
+typedef struct FileDescriptor FileDescriptor;
+
+struct Window {
+        MMapCache *cache;
+
+        bool keep_always;
+        bool in_unused;
+
+        void *ptr;
+        uint64_t offset;
+        int prot;
+        size_t size;
+
+        FileDescriptor *fd;
+
+        LIST_FIELDS(Window, by_fd);
+        LIST_FIELDS(Window, unused);
+
+        LIST_HEAD(Context, contexts);
+};
+
+struct Context {
+        MMapCache *cache;
+        unsigned id;
+        Window *window;
+
+        LIST_FIELDS(Context, by_window);
+};
+
+struct FileDescriptor {
+        MMapCache *cache;
+        int fd;
+        LIST_HEAD(Window, windows);
+};
+
+struct MMapCache {
+        int n_ref;
+
+        Hashmap *fds;
+        Hashmap *contexts;
+
+        unsigned n_windows;
+
+        LIST_HEAD(Window, unused);
+        Window *last_unused;
+};
+
+#define WINDOWS_MIN 64
+#define WINDOW_SIZE (8ULL*1024ULL*1024ULL)
+
+MMapCache* mmap_cache_new(void) {
+        MMapCache *m;
+
+        m = new0(MMapCache, 1);
+        if (!m)
+                return NULL;
+
+        m->n_ref = 1;
+        return m;
+}
+
+MMapCache* mmap_cache_ref(MMapCache *m) {
+        assert(m);
+        assert(m->n_ref > 0);
+
+        m->n_ref ++;
+        return m;
+}
+
+static void window_unlink(Window *w) {
+        Context *c;
+
+        assert(w);
+
+        if (w->ptr)
+                munmap(w->ptr, w->size);
+
+        if (w->fd)
+                LIST_REMOVE(Window, 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_FOREACH(by_window, c, w->contexts) {
+                assert(c->window == w);
+                c->window = NULL;
+        }
+}
+
+static void window_free(Window *w) {
+        assert(w);
+
+        window_unlink(w);
+        w->cache->n_windows--;
+        free(w);
+}
+
+static bool window_matches(Window *w, int fd, int prot, uint64_t offset, size_t size) {
+        assert(w);
+        assert(fd >= 0);
+        assert(size > 0);
+
+        return
+                w->fd &&
+                fd == w->fd->fd &&
+                prot == w->prot &&
+                offset >= w->offset &&
+                offset + size <= w->offset + w->size;
+}
+
+static Window *window_add(MMapCache *m) {
+        Window *w;
+
+        assert(m);
+
+        if (!m->last_unused || m->n_windows <= WINDOWS_MIN) {
+
+                /* Allocate a new window */
+                w = new0(Window, 1);
+                if (!w)
+                        return NULL;
+                m->n_windows++;
+        } else {
+
+                /* Reuse an existing one */
+                w = m->last_unused;
+                window_unlink(w);
+                zero(*w);
+        }
+
+        w->cache = m;
+        return w;
+}
+
+static void context_detach_window(Context *c) {
+        Window *w;
+
+        assert(c);
+
+        if (!c->window)
+                return;
+
+        w = c->window;
+        c->window = NULL;
+        LIST_REMOVE(Context, by_window, w->contexts, c);
+
+        if (!w->contexts && !w->keep_always) {
+                /* Not used anymore? */
+                LIST_PREPEND(Window, unused, c->cache->unused, w);
+                if (!c->cache->last_unused)
+                        c->cache->last_unused = w;
+
+                w->in_unused = true;
+        }
+}
+
+static void context_attach_window(Context *c, Window *w) {
+        assert(c);
+        assert(w);
+
+        if (c->window == w)
+                return;
+
+        context_detach_window(c);
+
+        if (w->in_unused) {
+                /* Used again? */
+                LIST_REMOVE(Window, unused, c->cache->unused, w);
+                if (c->cache->last_unused == w)
+                        c->cache->last_unused = w->unused_prev;
+
+                w->in_unused = false;
+        }
+
+        c->window = w;
+        LIST_PREPEND(Context, by_window, w->contexts, c);
+}
+
+static Context *context_add(MMapCache *m, unsigned id) {
+        Context *c;
+        int r;
+
+        assert(m);
+
+        c = hashmap_get(m->contexts, UINT_TO_PTR(id + 1));
+        if (c)
+                return c;
+
+        r = hashmap_ensure_allocated(&m->contexts, trivial_hash_func, trivial_compare_func);
+        if (r < 0)
+                return NULL;
+
+        c = new0(Context, 1);
+        if (!c)
+                return NULL;
+
+        c->cache = m;
+        c->id = id;
+
+        r = hashmap_put(m->contexts, UINT_TO_PTR(id + 1), c);
+        if (r < 0) {
+                free(c);
+                return NULL;
+        }
+
+        return c;
+}
+
+static void context_free(Context *c) {
+        assert(c);
+
+        context_detach_window(c);
+
+        if (c->cache)
+                assert_se(hashmap_remove(c->cache->contexts, UINT_TO_PTR(c->id + 1)));
+
+        free(c);
+}
+
+static void fd_free(FileDescriptor *f) {
+        assert(f);
+
+        while (f->windows)
+                window_free(f->windows);
+
+        if (f->cache)
+                assert_se(hashmap_remove(f->cache->fds, INT_TO_PTR(f->fd + 1)));
+
+        free(f);
+}
+
+static FileDescriptor* fd_add(MMapCache *m, int fd) {
+        FileDescriptor *f;
+        int r;
+
+        assert(m);
+        assert(fd >= 0);
+
+        f = hashmap_get(m->fds, INT_TO_PTR(fd + 1));
+        if (f)
+                return f;
+
+        r = hashmap_ensure_allocated(&m->fds, trivial_hash_func, trivial_compare_func);
+        if (r < 0)
+                return NULL;
+
+        f = new0(FileDescriptor, 1);
+        if (!f)
+                return NULL;
+
+        f->cache = m;
+        f->fd = fd;
+
+        r = hashmap_put(m->fds, UINT_TO_PTR(fd + 1), f);
+        if (r < 0) {
+                free(f);
+                return NULL;
+        }
+
+        return f;
+}
+
+static void mmap_cache_free(MMapCache *m) {
+        Context *c;
+        FileDescriptor *f;
+
+        assert(m);
+
+        while ((c = hashmap_first(m->contexts)))
+                context_free(c);
+
+        while ((f = hashmap_first(m->fds)))
+                fd_free(f);
+
+        while (m->unused)
+                window_free(m->unused);
+
+        free(m);
+}
+
+MMapCache* mmap_cache_unref(MMapCache *m) {
+        assert(m);
+        assert(m->n_ref > 0);
+
+        m->n_ref --;
+        if (m->n_ref == 0)
+                mmap_cache_free(m);
+
+        return NULL;
+}
+
+static int make_room(MMapCache *m) {
+        assert(m);
+
+        if (!m->last_unused)
+                return 0;
+
+        window_free(m->last_unused);
+        return 1;
+}
+
+static int try_context(
+                MMapCache *m,
+                int fd,
+                int prot,
+                unsigned context,
+                bool keep_always,
+                uint64_t offset,
+                size_t size,
+                void **ret) {
+
+        Context *c;
+
+        assert(m);
+        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)
+                return 0;
+
+        assert(c->id == context);
+
+        if (!c->window)
+                return 0;
+
+        if (!window_matches(c->window, fd, prot, offset, size)) {
+
+                /* Drop the reference to the window, since it's unnecessary now */
+                context_detach_window(c);
+                return 0;
+        }
+
+        c->window->keep_always = c->window->keep_always || keep_always;
+
+        *ret = (uint8_t*) c->window->ptr + (offset - c->window->offset);
+        return 1;
+}
+
+static int find_mmap(
+                MMapCache *m,
+                int fd,
+                int prot,
+                unsigned context,
+                bool keep_always,
+                uint64_t offset,
+                size_t size,
+                void **ret) {
+
+        FileDescriptor *f;
+        Window *w;
+        Context *c;
+
+        assert(m);
+        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)
+                return 0;
+
+        assert(f->fd == fd);
+
+        LIST_FOREACH(by_fd, w, f->windows)
+                if (window_matches(w, fd, prot, offset, size))
+                        break;
+
+        if (!w)
+                return 0;
+
+        c = context_add(m, context);
+        if (!c)
+                return -ENOMEM;
+
+        context_attach_window(c, w);
+        w->keep_always = w->keep_always || keep_always;
+
+        *ret = (uint8_t*) w->ptr + (offset - w->offset);
+        return 1;
+}
+
+static int add_mmap(
+                MMapCache *m,
+                int fd,
+                int prot,
+                unsigned context,
+                bool keep_always,
+                uint64_t offset,
+                size_t size,
+                struct stat *st,
+                void **ret) {
+
+        uint64_t woffset, wsize;
+        Context *c;
+        FileDescriptor *f;
+        Window *w;
+        void *d;
+        int r;
+
+        assert(m);
+        assert(m->n_ref > 0);
+        assert(fd >= 0);
+        assert(size > 0);
+        assert(ret);
+
+        woffset = offset & ~((uint64_t) page_size() - 1ULL);
+        wsize = size + (offset - woffset);
+        wsize = PAGE_ALIGN(wsize);
+
+        if (wsize < WINDOW_SIZE) {
+                uint64_t delta;
+
+                delta = PAGE_ALIGN((WINDOW_SIZE - wsize) / 2);
+
+                if (delta > offset)
+                        woffset = 0;
+                else
+                        woffset -= delta;
+
+                wsize = WINDOW_SIZE;
+        }
+
+        if (st) {
+                /* Memory maps that are larger then the files
+                   underneath have undefined behavior. Hence, clamp
+                   things to the file size if we know it */
+
+                if (woffset >= (uint64_t) st->st_size)
+                        return -EADDRNOTAVAIL;
+
+                if (woffset + wsize > (uint64_t) st->st_size)
+                        wsize = PAGE_ALIGN(st->st_size - woffset);
+        }
+
+        for (;;) {
+                d = mmap(NULL, wsize, prot, MAP_SHARED, fd, woffset);
+                if (d != MAP_FAILED)
+                        break;
+                if (errno != ENOMEM)
+                        return -errno;
+
+                r = make_room(m);
+                if (r < 0)
+                        return r;
+                if (r == 0)
+                        return -ENOMEM;
+        }
+
+        c = context_add(m, context);
+        if (!c)
+                return -ENOMEM;
+
+        f = fd_add(m, fd);
+        if (!f)
+                return -ENOMEM;
+
+        w = window_add(m);
+        if (!w)
+                return -ENOMEM;
+
+        w->keep_always = keep_always;
+        w->ptr = d;
+        w->offset = woffset;
+        w->prot = prot;
+        w->size = wsize;
+        w->fd = f;
+
+        LIST_PREPEND(Window, by_fd, f->windows, w);
+
+        context_detach_window(c);
+        c->window = w;
+        LIST_PREPEND(Context, by_window, w->contexts, c);
+
+        *ret = (uint8_t*) w->ptr + (offset - w->offset);
+        return 1;
+}
+
+int mmap_cache_get(
+                MMapCache *m,
+                int fd,
+                int prot,
+                unsigned context,
+                bool keep_always,
+                uint64_t offset,
+                size_t size,
+                struct stat *st,
+                void **ret) {
+
+        int r;
+
+        assert(m);
+        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)
+                return r;
+
+        /* Search for a matching mmap */
+        r = find_mmap(m, fd, prot, context, keep_always, offset, size, ret);
+        if (r != 0)
+                return r;
+
+        /* Create a new mmap */
+        return add_mmap(m, fd, prot, context, keep_always, offset, size, st, ret);
+}
+
+void mmap_cache_close_fd(MMapCache *m, int fd) {
+        FileDescriptor *f;
+
+        assert(m);
+        assert(fd >= 0);
+
+        f = hashmap_get(m->fds, INT_TO_PTR(fd + 1));
+        if (!f)
+                return;
+
+        fd_free(f);
+}
+
+void mmap_cache_close_context(MMapCache *m, unsigned context) {
+        Context *c;
+
+        assert(m);
+
+        c = hashmap_get(m->contexts, UINT_TO_PTR(context + 1));
+        if (!c)
+                return;
+
+        context_free(c);
+}