improve the mmap handling

* add frontend interfaces to file to get a mmaping
 * SECTION macro to encapsulate mmap access
 * mmap_address() translating an actual offset to address
 * add some tests
 * some test cosmetics

src/backend/file.c

@@ -154,3 +154,27 @@ lumiera_file_mmapings (LumieraFile self)
 
   return self->descriptor->mmapings;
 }
+
+
+LumieraMMap
+lumiera_file_mmap_acquire (LumieraFile self, LList acquirer, off_t start, size_t size)
+{
+  TRACE (file_dbg);
+  return lumiera_mmapings_mmap_acquire (lumiera_file_mmapings (self), self, acquirer, start, size);
+}
+
+
+void
+lumiera_file_release_mmap (LumieraFile self, LList acquirer, LumieraMMap map)
+{
+  TRACE (file_dbg);
+  lumiera_mmapings_release_mmap (lumiera_file_mmapings (self), acquirer, map);
+}
+
+/*
+// Local Variables:
+// mode: C
+// c-file-style: "gnu"
+// indent-tabs-mode: nil
+// End:
+*/

src/backend/file.h

@@ -51,6 +51,7 @@ typedef lumiera_file* LumieraFile;
 #include "backend/filedescriptor.h"
 #include "backend/filehandle.h"
 #include "backend/mmapings.h"
+#include "backend/mmap.h"
 
 /**
  * File modes:
@@ -146,6 +147,50 @@ void
 lumiera_file_handle_release (LumieraFile self);
 
 
+/**
+ * acquire a mmap which covers the given range
+ * @param self file from where the mmap shall be acquired
+ * @param acquirer list node of the new owner which will registered in the mmap
+ * @param start begin of the required range
+ * @param size requested size
+ * @return MMap object covering the requested range or NULL on error
+ * note: the chunksize for the file must be set prior accessing mmaps
+ */
+LumieraMMap
+lumiera_file_mmap_acquire (LumieraFile self, LList acquirer, off_t start, size_t size);
+
+
+/**
+ * release a previously acquired MMap object
+ * @param self file to which the map belongs
+ * @param acquirer holding node, used on require
+ * @param map object to be released
+ */
+void
+lumiera_file_release_mmap (LumieraFile self, LList acquirer, LumieraMMap map);
+
+
+/**
+ * helper macro for acquireing and releasing maped regions
+ * @param file the file from from where to acquire the mapped region
+ * @param start the start offset for the mmaped region
+ * @param size the length of the requested block
+ * @param addr name of a void* variable pointing to the requested memory
+ */
+#define LUMIERA_FILE_MMAP_SECTION(file, start, size, addr)                              \
+  for (LLIST_AUTO(user_##__LINE__); user_##__LINE__.next; user_##__LINE__.next = NULL)  \
+    for (LumieraMMap map_##__LINE__ =                                                   \
+           lumiera_file_mmap_acquire (file, &user_##__LINE__, start, size);             \
+         map_##__LINE__;                                                                \
+         ({                                                                             \
+           lumiera_file_release_mmap (file, &user_##__LINE__, map_##__LINE__);          \
+           map_##__LINE__ = NULL;                                                       \
+         }))                                                                            \
+      for (void* addr = lumiera_mmap_address (map_##__LINE__, start);                   \
+           addr;                                                                        \
+           addr = NULL)
+
+
 /**
  * Query the underlying mmapings object from a file
  * The MMapings only exists after a chunksize got set with lumiera_file_chunksize_set()
@@ -175,3 +220,10 @@ lumiera_file_chunksize_get (LumieraFile self);
 
 #endif
 
+/*
+// Local Variables:
+// mode: C
+// c-file-style: "gnu"
+// indent-tabs-mode: nil
+// End:
+*/

src/backend/mmap.h

@@ -78,13 +78,20 @@ LumieraMMap
 lumiera_mmap_new (LumieraFile file, off_t start, size_t size);
 
 
+/**
+ * Translate a 'external' offset to a address in memory
+ * @param self MMap object to query
+ * @param offset position on the mmaped file to get
+ * @return address in memory which relates to offset
+ */
 static inline void*
-lumiera_mmap_address (LumieraMMap self)
+lumiera_mmap_address (LumieraMMap self, off_t offset)
 {
-  return self->address;
+  REQUIRE (offset >= self->start, "offset before mmaped region");
+  REQUIRE (offset < self->start + (off_t)self->size, "offset after mmaped region");
+  return self?(self->address + (offset - self->start)):NULL;
 }
 
-
 void
 lumiera_mmap_delete (LumieraMMap self);
 

src/backend/mmapings.c

@@ -93,66 +93,66 @@ lumiera_mmapings_mmap_acquire (LumieraMMapings self, LumieraFile file, LList acq
 
   LumieraMMap ret = NULL;
 
-  LUMIERA_MUTEX_SECTION (mutex_sync, &self->lock)
-    {
-      REQUIRE (llist_is_empty (acquirer));
+  if (self)
+    LUMIERA_MUTEX_SECTION (mutex_sync, &self->lock)
+      {
+        REQUIRE (llist_is_empty (acquirer));
 
-      /* find first matching mmap, crude way */
-      LLIST_FOREACH (&self->mmaps, node)
-        {
-          TODO ("improve this selection algorithm, choose mmaps by size, move mfu to head etc");
+        /* find first matching mmap, crude way */
+        LLIST_FOREACH (&self->mmaps, node)
+          {
+            TODO ("improve this selection algorithm, choose mmaps by size, move mfu to head etc");
 
-          LumieraMMap mmap = LLIST_TO_STRUCTP (node, lumiera_mmap, searchnode);
+            LumieraMMap mmap = LLIST_TO_STRUCTP (node, lumiera_mmap, searchnode);
 
-          if (mmap->size >= size && mmap->start <= start && mmap->start+mmap->size >= start+size)
-            {
-              ret = mmap;
-              break;
-            }
-        }
+            if (mmap->size >= size && mmap->start <= start && mmap->start+mmap->size >= start+size)
+              {
+                ret = mmap;
+                break;
+              }
+          }
 
-      /* found? */
-      if (ret)
-        {
-          if (!ret->refcnt)
-            /* in cache, needs to me checked out */
-            lumiera_mmapcache_checkout (lumiera_mcache, ret);
-        }
-      else
-        {
-          /* create new mmap */
-          TRACE (mmapings_dbg, "mmap not found, creating");
-          ret = lumiera_mmap_new (file, start, size);
+        /* found? */
+        if (ret)
+          {
+            if (!ret->refcnt)
+              /* in cache, needs to me checked out */
+              lumiera_mmapcache_checkout (lumiera_mcache, ret);
+          }
+        else
+          {
+            /* create new mmap */
+            TRACE (mmapings_dbg, "mmap not found, creating");
+            ret = lumiera_mmap_new (file, start, size);
 
-          llist_insert_head (&self->mmaps, &ret->searchnode);
+            llist_insert_head (&self->mmaps, &ret->searchnode);
 
-          TODO ("sort search list?");
-        }
+            TODO ("sort search list?");
+          }
 
-      llist_insert_head (&ret->cachenode, acquirer);
-    }
+        llist_insert_head (&ret->cachenode, acquirer);
+      }
 
   return ret;
 }
 
-
 void
 lumiera_mmapings_release_mmap (LumieraMMapings self, LList acquirer, LumieraMMap map)
 {
   TRACE (mmapings_dbg);
 
-  LUMIERA_MUTEX_SECTION (mutex_sync, &self->lock)
-    {
-      llist_unlink (acquirer);
-      if (llist_is_empty (&map->cachenode))
-        {
-          TRACE (mmapcache_dbg, "checkin");
-          lumiera_mmapcache_checkin (lumiera_mcache, map);
-        }
-    }
+  if (self)
+    LUMIERA_MUTEX_SECTION (mutex_sync, &self->lock)
+      {
+        llist_unlink (acquirer);
+        if (llist_is_empty (&map->cachenode))
+          {
+            TRACE (mmapcache_dbg, "checkin");
+            lumiera_mmapcache_checkin (lumiera_mcache, map);
+          }
+      }
 }
 
-
 /*
 // Local Variables:
 // mode: C

tests/30mmap.tests

@@ -36,4 +36,16 @@ TEST "readonly file" mmap_readonly_file <<END
 return: 0
 END
 
+TEST "accessing file" file_access <<END
+return: 0
+END
+
+TEST "mmaped secion" mmap_section <<END
+return: 0
+END
+
+TEST "mmaped secion, error" mmap_section_err <<END
+return: !0
+END
+
 rm ,tmp-filemmap 2>/dev/null

tests/backend/test-filemmap.c

@@ -34,6 +34,7 @@
 #include "tests/test.h"
 
 #include <unistd.h>
+#include <string.h>
 #include <errno.h>
 #include <sys/mman.h>
 
@@ -133,9 +134,9 @@ TEST ("mmap_forget_releasing")
   llist user;
   llist_init (&user);
 
-  LumieraMMap mmap = lumiera_mmapings_mmap_acquire (mmaps, file, &user, 0, 100);
+  LumieraMMap map = lumiera_mmapings_mmap_acquire (mmaps, file, &user, 0, 100);
  
-  (void) mmap;  //lumiera_mmapings_release_mmap (mmaps, &user, mmap);
+  (void) map;  //lumiera_mmapings_release_mmap (mmaps, &user, mmap);
 
   lumiera_file_delete (file);
 
@@ -154,9 +155,9 @@ TEST ("mmap_simple")
 
   llist user;
   llist_init (&user);
-  LumieraMMap mmap = lumiera_mmapings_mmap_acquire (mmaps, file, &user, 0, 100);
+  LumieraMMap map = lumiera_mmapings_mmap_acquire (mmaps, file, &user, 0, 100);
 
-  lumiera_mmapings_release_mmap (mmaps, &user, mmap);
+  lumiera_mmapings_release_mmap (mmaps, &user, map);
 
   lumiera_file_delete (file);
 
@@ -181,17 +182,17 @@ TEST ("mmap_checkout_twice")
 
   llist user;
   llist_init (&user);
-  LumieraMMap mmap = lumiera_mmapings_mmap_acquire (mmaps, file, &user, 0, 100);
+  LumieraMMap map = lumiera_mmapings_mmap_acquire (mmaps, file, &user, 0, 100);
 
   llist user2;
   llist_init (&user2);
-  LumieraMMap mmap2 = lumiera_mmapings_mmap_acquire (mmaps, file, &user2, 0, 100);
+  LumieraMMap map2 = lumiera_mmapings_mmap_acquire (mmaps, file, &user2, 0, 100);
 
-  ENSURE (lumiera_mmap_address (mmap) == lumiera_mmap_address (mmap2));
+  ENSURE (map->address == map2->address);
 
-  lumiera_mmapings_release_mmap (mmaps, &user, mmap);
+  lumiera_mmapings_release_mmap (mmaps, &user, map);
 
-  lumiera_mmapings_release_mmap (mmaps, &user2, mmap2);
+  lumiera_mmapings_release_mmap (mmaps, &user2, map2);
 
   lumiera_file_delete (file);
 
@@ -216,13 +217,13 @@ TEST ("mmap_checkout_again")
 
   llist user;
   llist_init (&user);
-  LumieraMMap mmap = lumiera_mmapings_mmap_acquire (mmaps, file, &user, 0, 100);
-  lumiera_mmapings_release_mmap (mmaps, &user, mmap);
+  LumieraMMap map = lumiera_mmapings_mmap_acquire (mmaps, file, &user, 0, 100);
+  lumiera_mmapings_release_mmap (mmaps, &user, map);
 
   llist user2;
   llist_init (&user2);
-  LumieraMMap mmap2 = lumiera_mmapings_mmap_acquire (mmaps, file, &user2, 0, 100);
-  lumiera_mmapings_release_mmap (mmaps, &user2, mmap2);
+  LumieraMMap map2 = lumiera_mmapings_mmap_acquire (mmaps, file, &user2, 0, 100);
+  lumiera_mmapings_release_mmap (mmaps, &user2, map2);
 
   lumiera_file_delete (file);
 
@@ -249,8 +250,8 @@ TEST ("mmap_grow_existing_file")
   llist user;
   llist_init (&user);
 
-  LumieraMMap mmap = lumiera_mmapings_mmap_acquire (mmaps, file, &user, 0, 100);
-  lumiera_mmapings_release_mmap (mmaps, &user, mmap);
+  LumieraMMap map = lumiera_mmapings_mmap_acquire (mmaps, file, &user, 0, 100);
+  lumiera_mmapings_release_mmap (mmaps, &user, map);
 
   lumiera_file_delete (file);
 
@@ -276,8 +277,8 @@ TEST ("mmap_readonly_file")
   llist user;
   llist_init (&user);
 
-  LumieraMMap mmap = lumiera_mmapings_mmap_acquire (mmaps, file, &user, 0, 100);
-  lumiera_mmapings_release_mmap (mmaps, &user, mmap);
+  LumieraMMap map = lumiera_mmapings_mmap_acquire (mmaps, file, &user, 0, 100);
+  lumiera_mmapings_release_mmap (mmaps, &user, map);
 
   lumiera_file_delete (file);
 
@@ -292,6 +293,63 @@ TEST ("mmap_readonly_file")
 
 
 
+TEST ("file_access")
+{
+  lumiera_backend_init ();
+  LumieraFile file = lumiera_file_new (",tmp-filemmap", LUMIERA_FILE_RECREATE);
+  lumiera_file_chunksize_set (file, 4096);
+
+  llist user;
+  llist_init (&user);
+
+  LumieraMMap map = lumiera_file_mmap_acquire (file, &user, 10, 100);
+
+  char* addr = lumiera_mmap_address (map, 20);
+
+  strcpy (addr, "test");
+
+  lumiera_file_release_mmap (file, &user, map);
+
+  lumiera_file_delete (file);
+  lumiera_backend_destroy ();
+}
+
+
+
+TEST ("mmap_section")
+{
+  lumiera_backend_init ();
+  LumieraFile file = lumiera_file_new (",tmp-filemmap", LUMIERA_FILE_RECREATE);
+  lumiera_file_chunksize_set (file, 4096);
+
+  LUMIERA_FILE_MMAP_SECTION(file, 20, 20, addr)
+    {
+      strcpy (addr, "mmap section");
+    }
+
+  CHECK(lumiera_error_peek() == NULL);
+
+  lumiera_file_delete (file);
+  lumiera_backend_destroy ();
+}
+
+
+TEST ("mmap_section_err")
+{
+  lumiera_backend_init ();
+  LumieraFile file = lumiera_file_new (",tmp-filemmap", LUMIERA_FILE_RECREATE);
+  /* forgot to set lumiera_file_chunksize_set (file, 4096); */
+
+  LUMIERA_FILE_MMAP_SECTION(file, 20, 20, addr)
+    {
+      strcpy (addr, "mmap section");
+    }
+
+  CHECK(lumiera_error_peek() == NULL);
+
+  lumiera_file_delete (file);
+  lumiera_backend_destroy ();
+}
 
 
 #if 0