win: add UV_FS_O_FILEMAP

Reading and writing files using a memory file mapping can be
significantly faster on Windows.

PR-URL: libuv#2295
Reviewed-By: Bartosz Sosnowski <[email protected]>

.gitignore

@@ -51,6 +51,7 @@ Makefile.in
 /test/run-benchmarks
 /test/run-benchmarks.exe
 /test/run-benchmarks.dSYM
+test_file_*
 
 *.sln
 *.sln.cache

CMakeLists.txt

@@ -53,6 +53,8 @@ set(uv_test_sources
     test/test-fs-poll.c
     test/test-fs.c
     test/test-fs-readdir.c
+    test/test-fs-fd-hash.c
+    test/test-fs-open-flags.c
     test/test-get-currentexe.c
     test/test-get-loadavg.c
     test/test-get-memory.c

Makefile.am

@@ -184,6 +184,8 @@ test_run_tests_SOURCES = test/blackhole-server.c \
                          test/test-fs-poll.c \
                          test/test-fs.c \
                          test/test-fs-readdir.c \
+                         test/test-fs-fd-hash.c \
+                         test/test-fs-open-flags.c \
                          test/test-fork.c \
                          test/test-getters-setters.c \
                          test/test-get-currentexe.c \

docs/src/fs.rst

@@ -534,6 +534,14 @@ File open constants
 
     .. versionchanged:: 1.17.0 support is added for Windows.
 
+.. c:macro:: UV_FS_O_FILEMAP
+
+    Use a memory file mapping to access the file. When using this flag, the
+    file cannot be open multiple times concurrently.
+
+    .. note::
+        `UV_FS_O_FILEMAP` is only supported on Windows.
+
 .. c:macro:: UV_FS_O_NOATIME
 
     Do not update the file access time when the file is read.

include/uv/unix.h

@@ -481,6 +481,7 @@ typedef struct {
 #endif
 
 /* fs open() flags supported on other platforms: */
+#define UV_FS_O_FILEMAP       0
 #define UV_FS_O_RANDOM        0
 #define UV_FS_O_SHORT_LIVED   0
 #define UV_FS_O_SEQUENTIAL    0

include/uv/win.h

@@ -668,6 +668,7 @@ typedef struct {
 #define UV_FS_O_APPEND       _O_APPEND
 #define UV_FS_O_CREAT        _O_CREAT
 #define UV_FS_O_EXCL         _O_EXCL
+#define UV_FS_O_FILEMAP      0x20000000
 #define UV_FS_O_RANDOM       _O_RANDOM
 #define UV_FS_O_RDONLY       _O_RDONLY
 #define UV_FS_O_RDWR         _O_RDWR

src/win/core.c

@@ -204,6 +204,9 @@ static void uv_init(void) {
   /* Initialize winsock */
   uv_winsock_init();
 
+  /* Initialize FS */
+  uv_fs_init();
+
   /* Initialize signal stuff */
   uv_signals_init();
 

src/win/fs-fd-hash-inl.h

@@ -0,0 +1,178 @@
+#ifndef UV_WIN_FS_FD_HASH_INL_H_
+#define UV_WIN_FS_FD_HASH_INL_H_
+
+#include "uv.h"
+#include "internal.h"
+
+/* Files are only inserted in uv__fd_hash when the UV_FS_O_FILEMAP flag is
+ * specified. Thus, when uv__fd_hash_get returns true, the file mapping in the
+ * info structure should be used for read/write operations.
+ *
+ * If the file is empty, the mapping field will be set to
+ * INVALID_HANDLE_VALUE. This is not an issue since the file mapping needs to
+ * be created anyway when the file size changes.
+ *
+ * Since file descriptors are sequential integers, the modulo operator is used
+ * as hashing function. For each bucket, a single linked list of arrays is
+ * kept to minimize allocations. A statically allocated memory buffer is kept
+ * for the first array in each bucket. */
+
+
+#define UV__FD_HASH_SIZE 256
+#define UV__FD_HASH_GROUP_SIZE 16
+
+struct uv__fd_info_s {
+  int flags;
+  BOOLEAN is_directory;
+  HANDLE mapping;
+  LARGE_INTEGER size;
+  LARGE_INTEGER current_pos;
+};
+
+struct uv__fd_hash_entry_s {
+  uv_file fd;
+  struct uv__fd_info_s info;
+};
+
+struct uv__fd_hash_entry_group_s {
+  struct uv__fd_hash_entry_s entries[UV__FD_HASH_GROUP_SIZE];
+  struct uv__fd_hash_entry_group_s* next;
+};
+
+struct uv__fd_hash_bucket_s {
+  size_t size;
+  struct uv__fd_hash_entry_group_s* data;
+};
+
+
+static uv_mutex_t uv__fd_hash_mutex;
+
+static struct uv__fd_hash_entry_group_s
+  uv__fd_hash_entry_initial[UV__FD_HASH_SIZE * UV__FD_HASH_GROUP_SIZE];
+static struct uv__fd_hash_bucket_s uv__fd_hash[UV__FD_HASH_SIZE];
+
+
+INLINE static void uv__fd_hash_init(void) {
+  int i, err;
+
+  err = uv_mutex_init(&uv__fd_hash_mutex);
+  if (err) {
+    uv_fatal_error(err, "uv_mutex_init");
+  }
+
+  for (i = 0; i < ARRAY_SIZE(uv__fd_hash); ++i) {
+    uv__fd_hash[i].size = 0;
+    uv__fd_hash[i].data =
+        uv__fd_hash_entry_initial + i * UV__FD_HASH_GROUP_SIZE;
+  }
+}
+
+#define FIND_COMMON_VARIABLES                                                \
+  unsigned i;                                                                \
+  unsigned bucket = fd % ARRAY_SIZE(uv__fd_hash);                            \
+  struct uv__fd_hash_entry_s* entry_ptr = NULL;                              \
+  struct uv__fd_hash_entry_group_s* group_ptr;                               \
+  struct uv__fd_hash_bucket_s* bucket_ptr = &uv__fd_hash[bucket];
+
+#define FIND_IN_GROUP_PTR(group_size)                                        \
+  do {                                                                       \
+    for (i = 0; i < group_size; ++i) {                                       \
+      if (group_ptr->entries[i].fd == fd) {                                  \
+        entry_ptr = &group_ptr->entries[i];                                  \
+        break;                                                               \
+      }                                                                      \
+    }                                                                        \
+  } while (0)
+
+#define FIND_IN_BUCKET_PTR()                                                 \
+  do {                                                                       \
+    size_t first_group_size = bucket_ptr->size % UV__FD_HASH_GROUP_SIZE;     \
+    if (bucket_ptr->size != 0 && first_group_size == 0)                      \
+      first_group_size = UV__FD_HASH_GROUP_SIZE;                             \
+    group_ptr = bucket_ptr->data;                                            \
+    FIND_IN_GROUP_PTR(first_group_size);                                     \
+    for (group_ptr = group_ptr->next;                                        \
+         group_ptr != NULL && entry_ptr == NULL;                             \
+         group_ptr = group_ptr->next)                                        \
+      FIND_IN_GROUP_PTR(UV__FD_HASH_GROUP_SIZE);                             \
+  } while (0)
+
+INLINE static int uv__fd_hash_get(int fd, struct uv__fd_info_s* info) {
+  FIND_COMMON_VARIABLES
+
+  uv_mutex_lock(&uv__fd_hash_mutex);
+
+  FIND_IN_BUCKET_PTR();
+
+  if (entry_ptr != NULL) {
+    *info = entry_ptr->info;
+  }
+
+  uv_mutex_unlock(&uv__fd_hash_mutex);
+  return entry_ptr != NULL;
+}
+
+INLINE static void uv__fd_hash_add(int fd, struct uv__fd_info_s* info) {
+  FIND_COMMON_VARIABLES
+
+  uv_mutex_lock(&uv__fd_hash_mutex);
+
+  FIND_IN_BUCKET_PTR();
+
+  if (entry_ptr == NULL) {
+    i = bucket_ptr->size % UV__FD_HASH_GROUP_SIZE;
+
+    if (bucket_ptr->size != 0 && i == 0) {
+      struct uv__fd_hash_entry_group_s* new_group_ptr =
+        uv__malloc(sizeof(*new_group_ptr));
+      if (new_group_ptr == NULL) {
+        uv_fatal_error(ERROR_OUTOFMEMORY, "uv__malloc");
+      }
+      new_group_ptr->next = bucket_ptr->data;
+      bucket_ptr->data = new_group_ptr;
+    }
+
+    bucket_ptr->size += 1;
+    entry_ptr = &bucket_ptr->data->entries[i];
+    entry_ptr->fd = fd;
+  }
+
+  entry_ptr->info = *info;
+
+  uv_mutex_unlock(&uv__fd_hash_mutex);
+}
+
+INLINE static int uv__fd_hash_remove(int fd, struct uv__fd_info_s* info) {
+  FIND_COMMON_VARIABLES
+
+  uv_mutex_lock(&uv__fd_hash_mutex);
+
+  FIND_IN_BUCKET_PTR();
+
+  if (entry_ptr != NULL) {
+    *info = entry_ptr->info;
+
+    bucket_ptr->size -= 1;
+
+    i = bucket_ptr->size % UV__FD_HASH_GROUP_SIZE;
+    if (entry_ptr != &bucket_ptr->data->entries[i]) {
+      *entry_ptr = bucket_ptr->data->entries[i];
+    }
+
+    if (bucket_ptr->size != 0 &&
+        bucket_ptr->size % UV__FD_HASH_GROUP_SIZE == 0) {
+      struct uv__fd_hash_entry_group_s* old_group_ptr = bucket_ptr->data;
+      bucket_ptr->data = old_group_ptr->next;
+      uv__free(old_group_ptr);
+    }
+  }
+
+  uv_mutex_unlock(&uv__fd_hash_mutex);
+  return entry_ptr != NULL;
+}
+
+#undef FIND_COMMON_VARIABLES
+#undef FIND_IN_GROUP_PTR
+#undef FIND_IN_BUCKET_PTR
+
+#endif /* UV_WIN_FS_FD_HASH_INL_H_ */