Add a memory pool library implemented using cpp macros. The library
provides macros that can be used to create a type-specific memory pool
API.
Signed-off-by: David Barr <david.barr@xxxxxxxxxxxx>
Signed-off-by: Ramkumar Ramachandra <artagnon@xxxxxxxxx>
---
vcs-svn/obj_pool.h | 98 ++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 98 insertions(+), 0 deletions(-)
create mode 100644 vcs-svn/obj_pool.h
diff --git a/vcs-svn/obj_pool.h b/vcs-svn/obj_pool.h
new file mode 100644
index 0000000..84c8321
--- /dev/null
+++ b/vcs-svn/obj_pool.h
@@ -0,1 +1,98 @@
+#ifndef OBJ_POOL_H_
+#define OBJ_POOL_H_
+
+#include "git-compat-util.h"
+
+/*
+ * The obj_pool_gen() macro generates a type-specific memory pool
+ * implementation.
+ *
+ * Arguments:
+ *
+ * pre : Prefix for generated functions (ex: string_).
+ * obj_t : Type for treap data structure (ex: char).
+ * intial_capacity : The initial size of the memory pool (ex: 4096).
+ *
+ */
+#define obj_pool_gen(pre, obj_t, initial_capacity) \
+static struct { \
+ uint32_t size; \
+ uint32_t capacity; \
+ obj_t *base; \
+ FILE *file; \
+} pre##_pool = { 0, 0, NULL, NULL}; \
+static void pre##_init(void) \
+{ \
+ struct stat st; \
+ size_t ps = sysconf (_SC_PAGESIZE); \
+ /* Touch binary file before opening read/write */ \
+ pre##_pool.file = fopen(#pre ".bin", "a"); \
+ fclose(pre##_pool.file); \
+ /* Open, check size, compute capacity */ \
+ pre##_pool.file = fopen(#pre ".bin", "r+"); \
+ fstat(fileno(pre##_pool.file), &st); \
+ pre##_pool.size = st.st_size / sizeof(obj_t); \
+ pre##_pool.capacity = ((st.st_size + ps - 1) & ~(ps - 1)) / sizeof(obj_t); \
+ if (pre##_pool.capacity < initial_capacity) \
+ pre##_pool.capacity = initial_capacity; \
+ /* Truncate to calculated capacity and map to VM */ \
+ ftruncate(fileno(pre##_pool.file), pre##_pool.capacity * sizeof(obj_t)); \
+ pre##_pool.base = mmap(0, pre##_pool.capacity * sizeof(obj_t), \
+ PROT_READ | PROT_WRITE, MAP_SHARED, \
+ fileno(pre##_pool.file), 0); \
+} \
+static uint32_t pre##_alloc(uint32_t count) \
+{ \
+ uint32_t offset; \
+ if (pre##_pool.size + count > pre##_pool.capacity) { \
+ if (NULL == pre##_pool.base) \
+ pre##_init(); \
+ fsync(fileno(pre##_pool.file)); \
+ munmap(pre##_pool.base, \
+ pre##_pool.capacity * sizeof(obj_t)); \
+ pre##_pool.base = NULL; \
+ while (pre##_pool.size + count > pre##_pool.capacity) \
+ if (pre##_pool.capacity) \
+ pre##_pool.capacity *= 2; \
+ else \
+ pre##_pool.capacity = initial_capacity; \
+ ftruncate(fileno(pre##_pool.file), \
+ pre##_pool.capacity * sizeof(obj_t)); \
+ pre##_pool.base = \
+ mmap(0, pre##_pool.capacity * sizeof(obj_t), \
+ PROT_READ | PROT_WRITE, MAP_SHARED, \
+ fileno(pre##_pool.file), 0); \
+ } \
+ offset = pre##_pool.size; \
+ pre##_pool.size += count; \
+ return offset; \
+} \
+static void pre##_free(uint32_t count) \
+{ \
+ pre##_pool.size -= count; \
+} \
+static uint32_t pre##_offset(obj_t *obj) \
+{ \
+ return obj == NULL ? ~0 : obj - pre##_pool.base; \
+} \
+static obj_t *pre##_pointer(uint32_t offset) \
+{ \
+ return offset >= pre##_pool.size ? NULL : &pre##_pool.base[offset]; \
+} \
+static void pre##_reset(void) \
+{ \
+ if (pre##_pool.base) { \
+ fsync(fileno(pre##_pool.file)); \
+ munmap(pre##_pool.base, \
+ pre##_pool.capacity * sizeof(obj_t)); \
+ ftruncate(fileno(pre##_pool.file), \
+ pre##_pool.size * sizeof(obj_t)); \
+ fclose(pre##_pool.file); \
+ } \
+ pre##_pool.base = NULL; \
+ pre##_pool.size = 0; \
+ pre##_pool.capacity = 0; \
+ pre##_pool.file = NULL; \
+}
+
+#endif
--
1.7.1
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