From: Lennart Poettering <lennart@poettering.net>
Date: Fri, 17 Aug 2012 23:46:20 +0000 (+0200)
Subject: mmap: resize arrays dynamically
X-Git-Tag: v189~43
X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=commitdiff_plain;h=84168d8068bb67dcd5468ab3b376535d81643aef;ds=inline

mmap: resize arrays dynamically
---

diff --git a/src/journal/journal-file.c b/src/journal/journal-file.c
index df991a4a0..c6b25ce54 100644
--- a/src/journal/journal-file.c
+++ b/src/journal/journal-file.c
@@ -2003,10 +2003,7 @@ int journal_file_open(
         if (mmap_cache)
                 f->mmap = mmap_cache_ref(mmap_cache);
         else {
-                /* One context for each type, plus the zeroth catchall
-                 * context. One fd for the file plus one for each type
-                 * (which we need during verification */
-                f->mmap = mmap_cache_new(_OBJECT_TYPE_MAX, 1 + _OBJECT_TYPE_MAX);
+                f->mmap = mmap_cache_new();
                 if (!f->mmap) {
                         r = -ENOMEM;
                         goto fail;
diff --git a/src/journal/journald.c b/src/journal/journald.c
index d431953f0..f74c46158 100644
--- a/src/journal/journald.c
+++ b/src/journal/journald.c
@@ -2794,7 +2794,7 @@ static int server_init(Server *s) {
         if (!s->user_journals)
                 return log_oom();
 
-        s->mmap = mmap_cache_new(_OBJECT_TYPE_MAX, USER_JOURNALS_MAX + 2);
+        s->mmap = mmap_cache_new();
         if (!s->mmap)
                 return log_oom();
 
diff --git a/src/journal/mmap-cache.c b/src/journal/mmap-cache.c
index 9782139f5..69efb20ad 100644
--- a/src/journal/mmap-cache.c
+++ b/src/journal/mmap-cache.c
@@ -30,7 +30,10 @@
 #include "mmap-cache.h"
 
 #define WINDOW_SIZE (8ULL*1024ULL*1024ULL)
-#define WINDOWS_MAX 32
+
+#define DEFAULT_WINDOWS_MAX 64
+#define DEFAULT_FDS_MAX 32
+#define DEFAULT_CONTEXTS_MAX 32
 
 typedef struct Window {
         int fd;
@@ -236,19 +239,16 @@ static void mmap_cache_free(MMapCache *m) {
         free(m);
 }
 
-MMapCache* mmap_cache_new(unsigned contexts_max, unsigned fds_max) {
+MMapCache* mmap_cache_new(void) {
         MMapCache *m;
 
-        assert(contexts_max > 0);
-        assert(fds_max > 0);
-
         m = new0(MMapCache, 1);
         if (!m)
                 return NULL;
 
-        m->contexts_max = contexts_max;
-        m->fds_max = fds_max;
-        m->windows_max = MAX(m->contexts_max, WINDOWS_MAX);
+        m->contexts_max = DEFAULT_CONTEXTS_MAX;
+        m->fds_max = DEFAULT_FDS_MAX;
+        m->windows_max = DEFAULT_WINDOWS_MAX;
         m->n_ref = 1;
         m->lru_first = (unsigned) -1;
         m->lru_last = (unsigned) -1;
@@ -465,8 +465,18 @@ static int mmap_cache_get_fd_index(MMapCache *m, int fd, unsigned *fd_index) {
         if (r != 0)
                 return r;
 
-        if (m->n_fds >= m->fds_max)
-                return -E2BIG;
+        if (m->n_fds >= m->fds_max) {
+                unsigned k;
+                FileDescriptor *n;
+
+                k = m->n_fds * 2;
+                n = realloc(m->by_fd, sizeof(FileDescriptor) * k);
+                if (!n)
+                        return -ENOMEM;
+
+                m->fds_max = k;
+                m->by_fd = n;
+        }
 
         j = m->by_fd + m->n_fds ++;
         j->fd = fd;
@@ -580,10 +590,33 @@ int mmap_cache_get(
 
         assert(m);
         assert(fd >= 0);
-        assert(context < m->contexts_max);
         assert(size > 0);
         assert(ret);
 
+        if (context >= m->contexts_max) {
+                unsigned k, *n;
+                Window *w;
+
+                /* Increase the number of contexts if necessary, and
+                 * make sure we have twice the number of windows */
+
+                k = context * 2;
+                n = realloc(m->by_context, sizeof(unsigned) * k);
+                if (!n)
+                        return -ENOMEM;
+                memset(n + m->contexts_max, -1, (k - m->contexts_max) * sizeof(unsigned));
+                m->contexts_max = k;
+                m->by_context = n;
+
+                k = MAX(m->windows_max, m->contexts_max*2);
+                w = realloc(m->windows, sizeof(Window) * k);
+                if (!w)
+                        return -ENOMEM;
+
+                m->windows_max = k;
+                m->windows = w;
+        }
+
         /* Maybe the current pointer for this context is already the
          * right one? */
         r = mmap_cache_current(m, fd, context, offset, size, ret);
diff --git a/src/journal/mmap-cache.h b/src/journal/mmap-cache.h
index 984b75996..aae454435 100644
--- a/src/journal/mmap-cache.h
+++ b/src/journal/mmap-cache.h
@@ -25,7 +25,7 @@
 
 typedef struct MMapCache MMapCache;
 
-MMapCache* mmap_cache_new(unsigned contexts_max, unsigned fds_max);
+MMapCache* mmap_cache_new(void);
 MMapCache* mmap_cache_ref(MMapCache *m);
 MMapCache* mmap_cache_unref(MMapCache *m);
 
diff --git a/src/journal/sd-journal.c b/src/journal/sd-journal.c
index 41526b35b..725c979c8 100644
--- a/src/journal/sd-journal.c
+++ b/src/journal/sd-journal.c
@@ -1439,10 +1439,7 @@ static sd_journal *journal_new(int flags, const char *path) {
                 return NULL;
         }
 
-        /* One context for each type, plus the zeroth catchall
-         * context. One fd for each file plus one for each type, which
-         * is need when verifying things */
-        j->mmap = mmap_cache_new(_OBJECT_TYPE_MAX, JOURNAL_FILES_MAX + _OBJECT_TYPE_MAX);
+        j->mmap = mmap_cache_new();
         if (!j->mmap) {
                 hashmap_free(j->files);
                 hashmap_free(j->directories_by_path);