storage: introduce shm/pmem backed datapool abstraction

This patch creates a datapool abstraction for managing large amounts
of contiguous memory, and adds two implementations:
 - shm, backed by shared memory allocated through cc_alloc
 - pmem, backed by memory-mapped file managed through libpmem

The default implementation, datapool_shm, currently does not differ from
simply managing memory through cc_alloc/cc_free.

The datapool_pmem implementation, which can be enabled through
-DUSE_PMEM=ON, allows for durable (persistent) implementations of the
storage layer as it attempts to recover the previous content
of the managed memory.

CMakeLists.txt

@@ -47,6 +47,7 @@ option(TARGET_RESPCLI "build resp-cli binary" ON)
 option(HAVE_RUST "build features written in rust" OFF)
 option(RUST_USE_MUSL "build rust deps against musl" OFF)
 option(BUILD_AND_INSTALL_CHECK "build our own version of check and link against it" OFF)
+option(USE_PMEM "build persistent memory features" OFF)
 
 option(COVERAGE "code coverage" OFF)
 
@@ -126,7 +127,10 @@ add_subdirectory(${CCOMMON_SOURCE_DIR} ${PROJECT_BINARY_DIR}/ccommon)
 include(FindPackageHandleStandardArgs)
 set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${PROJECT_SOURCE_DIR}/cmake")
 
+find_package(PkgConfig QUIET)
+
 find_package(Check)
+
 if(NOT CHECK_FOUND)
     message(WARNING "Check is required to build and run tests")
 endif(NOT CHECK_FOUND)
@@ -137,6 +141,14 @@ if(CHECK_FOUND)
     endif(NOT CHECK_WORKING)
 endif(CHECK_FOUND)
 
+if (USE_PMEM)
+    if(PKG_CONFIG_FOUND)
+        pkg_check_modules(LIBPMEM REQUIRED libpmem>=1.0)
+    else()
+        find_package(LIBPMEM REQUIRED 1.0)
+    endif()
+endif(USE_PMEM)
+
 find_package(Threads)
 
 if(TARGET_CDB)

deps/ccommon/include/cc_mm.h

@@ -66,6 +66,9 @@ extern "C" {
 #define cc_munmap(_p, _s)                                       \
     _cc_munmap(_p, (size_t)(_s), __FILE__, __LINE__)
 
+#define cc_alloc_usable_size(_p)                                \
+    _cc_alloc_usable_size(_p, __FILE__, __LINE__)
+
 void * _cc_alloc(size_t size, const char *name, int line);
 void * _cc_zalloc(size_t size, const char *name, int line);
 void * _cc_calloc(size_t nmemb, size_t size, const char *name, int line);
@@ -74,6 +77,7 @@ void * _cc_realloc_move(void *ptr, size_t size, const char *name, int line);
 void _cc_free(void *ptr, const char *name, int line);
 void * _cc_mmap(size_t size, const char *name, int line);
 int _cc_munmap(void *p, size_t size, const char *name, int line);
+size_t _cc_alloc_usable_size(void *ptr, const char *name, int line);
 
 #ifdef __cplusplus
 }

deps/ccommon/src/cc_mm.c

@@ -27,6 +27,10 @@
 /* TODO(yao): detect OS in one place and use one variable everywhere */
 #if defined(__APPLE__) && defined(__MACH__)
 #   define MAP_ANONYMOUS MAP_ANON
+#include <malloc/malloc.h>
+#define malloc_usable_size malloc_size
+#else
+#include <malloc.h>
 #endif
 
 void *
@@ -167,3 +171,10 @@ _cc_munmap(void *p, size_t size, const char *name, int line)
 
     return status;
 }
+
+size_t
+_cc_alloc_usable_size(void *ptr, const char *name, int line)
+{
+    log_vverb("malloc_usable_size(%p) @ %s:%d", ptr, name, line);
+    return malloc_usable_size(ptr);
+}

src/CMakeLists.txt

@@ -5,6 +5,7 @@ add_subdirectory(protocol ${PROJECT_BINARY_DIR}/protocol)
 add_subdirectory(storage ${PROJECT_BINARY_DIR}/storage)
 add_subdirectory(time ${PROJECT_BINARY_DIR}/time)
 add_subdirectory(util ${PROJECT_BINARY_DIR}/util)
+add_subdirectory(datapool ${PROJECT_BINARY_DIR}/datapool)
 
 # executables
 add_custom_target(service)

src/datapool/CMakeLists.txt

@@ -0,0 +1,9 @@
+add_library(datapool)
+
+if(USE_PMEM)
+    target_sources(datapool PRIVATE datapool_pmem.c)
+    target_include_directories(datapool PRIVATE ${LIBPMEM_INCLUDE_DIRS})
+    target_link_libraries(datapool ${LIBPMEM_LIBRARIES})
+else()
+    target_sources(datapool PRIVATE datapool_shm.c)
+endif(USE_PMEM)

src/datapool/datapool.h

@@ -0,0 +1,12 @@
+#pragma once
+
+#include <stddef.h>
+
+struct datapool;
+
+struct datapool *datapool_open(const char *path, size_t size,
+	int *fresh);
+void datapool_close(struct datapool *pool);
+
+void *datapool_addr(struct datapool *pool);
+size_t datapool_size(struct datapool *pool);

src/datapool/datapool_pmem.c

@@ -0,0 +1,217 @@
+/*
+ * File-backed datapool.
+ * Retains its contents if the pool has been closed correctly.
+ *
+ */
+#include "datapool.h"
+
+#include <cc_mm.h>
+#include <cc_debug.h>
+
+#include <inttypes.h>
+
+#include <libpmem.h>
+
+#define DATAPOOL_SIGNATURE ("PELIKAN") /* 8 bytes */
+#define DATAPOOL_SIGNATURE_LEN (sizeof(DATAPOOL_SIGNATURE))
+#define DATAPOOL_HEADER_LEN 4096
+#define DATAPOOL_VERSION 1
+
+#define DATAPOOL_FLAG_DIRTY (1 << 0)
+#define DATAPOOL_VALID_FLAGS (DATAPOOL_FLAG_DIRTY)
+
+/*
+ * Header at the beginning of the file, it's verified every time the pool is
+ * opened.
+ */
+struct datapool_header {
+    uint8_t signature[DATAPOOL_SIGNATURE_LEN];
+    uint64_t version;
+    uint64_t size;
+    uint64_t flags;
+    uint8_t unused[DATAPOOL_HEADER_LEN - 32];
+};
+
+struct datapool {
+    void *addr;
+
+    struct datapool_header *hdr;
+    void *user_addr;
+    size_t mapped_len;
+    int is_pmem;
+    int file_backed;
+};
+
+static void
+datapool_sync_hdr(struct datapool *pool)
+{
+    pmem_msync(pool->hdr, DATAPOOL_HEADER_LEN);
+}
+
+static void
+datapool_sync(struct datapool *pool)
+{
+    pmem_msync(pool->addr, pool->mapped_len);
+}
+
+static int
+datapool_valid(struct datapool *pool)
+{
+    if (memcmp(pool->hdr->signature,
+          DATAPOOL_SIGNATURE, DATAPOOL_SIGNATURE_LEN) != 0) {
+        log_info("no signature found in datapool");
+        return 0;
+    }
+
+    if (pool->hdr->version != DATAPOOL_VERSION) {
+        log_info("incompatible datapool version (is: %d, expecting: %d)",
+            pool->hdr->version, DATAPOOL_SIGNATURE);
+        return 0;
+    }
+
+    if (pool->hdr->size == 0) {
+        log_error("datapool has 0 size");
+        return 0;
+    }
+
+    if (pool->hdr->size > pool->mapped_len) {
+        log_error("datapool has invalid size (is: %d, expecting: %d)",
+            pool->mapped_len, pool->hdr->size);
+        return 0;
+    }
+
+    if (pool->hdr->flags & ~DATAPOOL_VALID_FLAGS) {
+        log_error("datapool has invalid flags set");
+        return 0;
+    }
+
+    if (pool->hdr->flags & DATAPOOL_FLAG_DIRTY) {
+        log_info("datapool has a valid header but is dirty");
+        return 0;
+    }
+
+    return 1;
+}
+
+static void
+datapool_initialize(struct datapool *pool)
+{
+    log_info("initializing fresh datapool");
+
+    /* 1. clear the header from any leftovers */
+    memset(pool->hdr, 0, DATAPOOL_HEADER_LEN);
+    datapool_sync_hdr(pool);
+
+    /* 2. fill in the data */
+    pool->hdr->version = DATAPOOL_VERSION;
+    pool->hdr->size = pool->mapped_len;
+    pool->hdr->flags = 0;
+    datapool_sync_hdr(pool);
+
+    /* 3. set the signature */
+    memcpy(pool->hdr->signature, DATAPOOL_SIGNATURE, DATAPOOL_SIGNATURE_LEN);
+    datapool_sync_hdr(pool);
+}
+
+static void
+datapool_flag_set(struct datapool *pool, int flag)
+{
+    pool->hdr->flags |= flag;
+    datapool_sync_hdr(pool);
+}
+
+static void
+datapool_flag_clear(struct datapool *pool, int flag)
+{
+    pool->hdr->flags &= ~flag;
+    datapool_sync_hdr(pool);
+}
+
+/*
+ * Opens, and if necessary initializes, a datapool that resides in the given
+ * file. If no file is provided, the pool is allocated through cc_zalloc.
+ *
+ * The the datapool to retain its contents, the datapool_close() call must
+ * finish successfully.
+ */
+struct datapool *
+datapool_open(const char *path, size_t size, int *fresh)
+{
+    struct datapool *pool = cc_alloc(sizeof(*pool));
+    if (pool == NULL) {
+        log_error("unable to create allocate memory for pmem mapping");
+        goto err_alloc;
+    }
+
+    size_t map_size = size + sizeof(struct datapool_header);
+
+    if (path == NULL) { /* fallback to DRAM if pmem is not configured */
+        pool->addr = cc_zalloc(map_size);
+        pool->mapped_len = map_size;
+        pool->is_pmem = 0;
+        pool->file_backed = 0;
+    } else {
+        pool->addr = pmem_map_file(path, map_size, PMEM_FILE_CREATE, 0600,
+            &pool->mapped_len, &pool->is_pmem);
+        pool->file_backed = 1;
+    }
+
+    if (pool->addr == NULL) {
+        log_error(pmem_errormsg());
+        goto err_map;
+    }
+
+    log_info("mapped datapool %s with size %llu, is_pmem: %d",
+        path, pool->mapped_len, pool->is_pmem);
+
+    pool->hdr = pool->addr;
+    pool->user_addr = (uint8_t *)pool->addr + sizeof(struct datapool_header);
+
+    if (fresh)
+        *fresh = 0;
+
+    if (datapool_valid(pool))
+        goto out;
+
+    if (fresh)
+        *fresh = 1;
+
+    datapool_initialize(pool);
+
+out:
+    datapool_flag_set(pool, DATAPOOL_FLAG_DIRTY);
+
+    return pool;
+
+err_map:
+    cc_free(pool);
+err_alloc:
+    return NULL;
+}
+
+void
+datapool_close(struct datapool *pool)
+{
+    datapool_sync(pool);
+    datapool_flag_clear(pool, DATAPOOL_FLAG_DIRTY);
+
+    if (pool->file_backed)
+        pmem_unmap(pool->addr, pool->mapped_len);
+    else
+        cc_free(pool->addr);
+
+    cc_free(pool);
+}
+
+void *
+datapool_addr(struct datapool *pool)
+{
+    return pool->user_addr;
+}
+
+size_t
+datapool_size(struct datapool *pool)
+{
+    return pool->mapped_len - sizeof(struct datapool_header);
+}
+

src/datapool/datapool_shm.c

@@ -0,0 +1,42 @@
+/*
+ * Anonymous shared memory backed datapool.
+ * Loses all its contents after closing.
+ */
+#include "datapool.h"
+
+#include <cc_debug.h>
+#include <cc_mm.h>
+
+struct datapool *
+datapool_open(const char *path, size_t size, int *fresh)
+{
+    if (path != NULL) {
+        log_warn("attempted to open a file-based data pool without"
+            "pmem features enabled");
+        return NULL;
+    }
+
+    if (fresh)
+        *fresh = 1;
+
+    return cc_zalloc(size);
+}
+
+void
+datapool_close(struct datapool *pool)
+{
+    cc_free(pool);
+}
+
+void *
+datapool_addr(struct datapool *pool)
+{
+    return pool;
+}
+
+size_t
+datapool_size(struct datapool *pool)
+{
+    return cc_alloc_usable_size(pool);
+}
+

test/CMakeLists.txt

@@ -7,5 +7,8 @@ add_subdirectory(protocol)
 add_subdirectory(hotkey)
 add_subdirectory(storage)
 add_subdirectory(time)
+if(USE_PMEM)
+    add_subdirectory(datapool)
+endif()
 
 add_subdirectory(integration)

test/datapool/CMakeLists.txt

@@ -0,0 +1,12 @@
+set(suite datapool)
+set(test_name check_${suite})
+
+set(source check_${suite}.c)
+
+add_executable(${test_name} ${source})
+target_link_libraries(${test_name} ${suite})
+target_link_libraries(${test_name} ccommon-static ${CHECK_LIBRARIES})
+target_link_libraries(${test_name} datapool)
+
+add_dependencies(check ${test_name})
+add_test(${test_name} ${test_name})