Adding memory mapped I/O to ethash_full_new

CMakeLists.txt

@@ -21,7 +21,7 @@ set(FILES 	util.c
           	data_sizes.h)
 
 if (MSVC)
-	list(APPEND FILES io_win32.c)
+	list(APPEND FILES io_win32.c mmap_win32.c)
 else()
 	list(APPEND FILES io_posix.c)
 endif()

ethash.h

@@ -170,6 +170,8 @@ ethash_cache *ethash_light_acquire_cache(ethash_light_t light);
 /**
  * Allocate and initialize a new ethash_full handler
  *
+ * @param dirname   The directory in which to put the DAG file.
+ * @param seedhash  The seed hash of the block. Used in the DAG file naming.
  * @param params    The parameters to initialize it with. We are interested in
  *                  the full_size from here
  * @param cache     A cache object to use that was allocated with @ref ethash_cache_new().
@@ -183,7 +185,9 @@ ethash_cache *ethash_light_acquire_cache(ethash_light_t light);
  * @return          Newly allocated ethash_full handler or NULL in case of
  *                  ERRNOMEM or invalid parameters used for @ref ethash_compute_full_data()
  */
-ethash_full_t ethash_full_new(ethash_params const* params,
+ethash_full_t ethash_full_new(char const *dirname,
+	const ethash_h256_t *seed_hash,
+	ethash_params const* params,
 	ethash_cache const* cache,
 	ethash_callback_t callback);
 /**

internal.c

@@ -23,11 +23,14 @@
 #include <assert.h>
 #include <inttypes.h>
 #include <stddef.h>
+#include <errno.h>
+#include "mmap.h"
 #include "ethash.h"
 #include "fnv.h"
 #include "endian.h"
 #include "internal.h"
 #include "data_sizes.h"
+#include "io.h"
 
 #ifdef WITH_CRYPTOPP
 
@@ -121,11 +124,9 @@ void ethash_calculate_dag_item(node *const ret,
 	uint32_t num_parent_nodes = (uint32_t) (params->cache_size / sizeof(node));
 	node const *cache_nodes = (node const *) cache->mem;
 	node const *init = &cache_nodes[node_index % num_parent_nodes];
-
 	memcpy(ret, init, sizeof(node));
 	ret->words[0] ^= node_index;
 	SHA3_512(ret->bytes, ret->bytes, sizeof(node));
-
 #if defined(_M_X64) && ENABLE_SSE
 	__m128i const fnv_prime = _mm_set1_epi32(FNV_PRIME);
 	__m128i xmm0 = ret->xmm[0];
@@ -176,7 +177,6 @@ bool ethash_compute_full_data(void *mem,
 		return false;
 	}
 	node *full_nodes = mem;
-
 	// now compute full nodes
 	for (unsigned n = 0; n != (params->full_size / sizeof(node)); ++n) {
 		ethash_calculate_dag_item(&(full_nodes[n]), n, params, cache);
@@ -277,7 +277,6 @@ void ethash_quick_hash(ethash_h256_t *return_hash,
 					   const uint64_t nonce,
 					   ethash_h256_t const *mix_hash)
 {
-
 	uint8_t buf[64 + 32];
 	memcpy(buf, header_hash, 32);
 	fix_endian64_same(nonce);
@@ -353,21 +352,50 @@ ethash_cache *ethash_light_acquire_cache(ethash_light_t light)
 	return ret;
 }
 
-ethash_full_t ethash_full_new(ethash_params const* params,
+ethash_full_t ethash_full_new(char const *dirname,
+	const ethash_h256_t *seed_hash,
+	ethash_params const* params,
 	ethash_cache const* cache,
 	ethash_callback_t callback)
 {
 	struct ethash_full *ret;
+	int fd;
+	FILE *f = NULL;
+	bool match = false;
 	ret = calloc(sizeof(*ret), 1);
 	if (!ret) {
 		return NULL;
 	}
 
 	ret->cache = (ethash_cache*)cache;
-	ret->data = malloc((size_t)params->full_size);
+	ret->file_size = (size_t)params->full_size;
-	if (!ret->data) {
+	switch (ethash_io_prepare(dirname, *seed_hash, &f, (size_t)params->full_size)) {
+	case ETHASH_IO_FAIL:
+		goto fail_free_full;
+	case ETHASH_IO_MEMO_MATCH:
+		match = true;
+	case ETHASH_IO_MEMO_MISMATCH:
+		ret->file = f;
+		if ((fd = fileno(ret->file)) == -1) {
 			goto fail_free_full;
 		}
+		ret->data = mmap(
+			NULL,
+			(size_t)params->full_size,
+			PROT_READ | PROT_WRITE,
+			MAP_SHARED,
+			fd,
+			0
+		);
+		if (ret->data == MAP_FAILED) {
+			goto fail_close_file;
+		}
+		if (match) {
+			return ret;
+		}
+		break;
+	}
+
 	if (!ethash_compute_full_data(ret->data, params, cache)) {
 		goto fail_free_full_data;
 	}
@@ -375,7 +403,10 @@ ethash_full_t ethash_full_new(ethash_params const* params,
 	return ret;
 
 fail_free_full_data:
-	free(ret->data);
+	// could check that munmap(..) == 0 but even if it did not can't really do anything here
+	munmap(ret->data, (size_t)params->full_size);
+fail_close_file:
+	fclose(ret->file);
 fail_free_full:
 	free(ret);
 	return NULL;
@@ -386,7 +417,11 @@ void ethash_full_delete(ethash_full_t full)
 	if (full->cache) {
 		ethash_cache_delete(full->cache);
 	}
-	free(full->data);
+	// could check that munmap(..) == 0 but even if it did not can't really do anything here
+	munmap(full->data, full->file_size);
+	if (full->file) {
+		fclose(full->file);
+	}
 	free(full);
 }
 

internal.h

@@ -37,6 +37,7 @@ struct ethash_light {
 
 struct ethash_full {
 	FILE *file;
+	size_t file_size;
 	ethash_cache *cache;
 	node *data;
 	ethash_callback_t callback;

io.h

@@ -52,12 +52,18 @@ enum ethash_io_rc {
  * @param[in] seedhash   The seedhash of the current block number, used in the
  *                       naming of the file as can be seen from the spec at:
  *                       https://github.com/ethereum/wiki/wiki/Ethash-DAG
- * @param[out] f         If the hash/revision combo matched then this will point
+ * @param[out] f         If there was no failure then this will point to an open
- *                       to an opened file handler for that file. User will then
+ *                       file descriptor. User is responsible for closing it.
- *                       have to close it.
+ *                       In the case of memo match then the file is open on read
+ *                       mode, while on the case of mismatch a new file is created
+ *                       on write mode
+ * @param[in] file_size  The size that the DAG file should have on disk
  * @return               For possible return values @see enum ethash_io_rc
  */
-enum ethash_io_rc ethash_io_prepare(char const *dirname, ethash_h256_t seedhash, FILE **f);
+enum ethash_io_rc ethash_io_prepare(char const *dirname,
+	ethash_h256_t const seedhash,
+	FILE **f,
+	size_t file_size);
 
 /**
  * An fopen wrapper for no-warnings crossplatform fopen.
@@ -91,7 +97,7 @@ FILE *ethash_fopen(const char *file_name, const char *mode);
 char *ethash_strncat(char *dest, size_t dest_size, const char *src, size_t count);
 
 static inline bool ethash_io_mutable_name(uint32_t revision,
-                                          ethash_h256_t *seed_hash,
+	ethash_h256_t const* seed_hash,
 	char* output)
 {
     uint64_t hash = *((uint64_t*)seed_hash);

io_posix.c

@@ -38,8 +38,9 @@ char *ethash_strncat(char *dest, size_t dest_size, const char *src, size_t count
 }
 
 enum ethash_io_rc ethash_io_prepare(char const *dirname,
-	ethash_h256_t seedhash,
+	ethash_h256_t const seedhash,
-	FILE **output_file)
+	FILE **output_file,
+	size_t file_size)
 {
 	char mutable_name[DAG_MUTABLE_NAME_MAX_SIZE];
 	enum ethash_io_rc ret = ETHASH_IO_FAIL;
@@ -57,14 +58,28 @@ enum ethash_io_rc ethash_io_prepare(char const *dirname,
 	}
 
 	// try to open the file
-	FILE *f = ethash_fopen(tmpfile, "rb");
+	FILE *f = ethash_fopen(tmpfile, "rb+");
-	if (!f) {
+	if (f) {
+		// TODO: check for file size
+	} else {
 		// file does not exist, will need to be created
-		ret = ETHASH_IO_MEMO_MISMATCH;
+		f = ethash_fopen(tmpfile, "wb+");
+		if (!f) {
 			goto free_memo;
 		}
+		// make sure it's of the proper size
+		if (fseek(f, file_size - 1, SEEK_SET) != 0) {
+			fclose(f);
+			goto free_memo;
+		}
+		fputc('\n', f);
+		fflush(f);
+		ret = ETHASH_IO_MEMO_MISMATCH;
+		goto set_file;
+	}
 
 	ret = ETHASH_IO_MEMO_MATCH;
+set_file:
 	*output_file = f;
 free_memo:
 	free(tmpfile);

io_win32.c

@@ -35,7 +35,10 @@ char *ethash_strncat(char *dest, size_t dest_size, const char *src, size_t count
 	return strncat_s(dest, dest_size, src, count) == 0 ? dest : NULL;
 }
 
-enum ethash_io_rc ethash_io_prepare(char const *dirname, ethash_h256_t seedhash)
+enum ethash_io_rc ethash_io_prepare(char const *dirname,
+	ethash_h256_t const seedhash,
+	FILE **output_file,
+	size_t file_size)
 {
 	char mutable_name[DAG_MUTABLE_NAME_MAX_SIZE];
 	enum ethash_io_rc ret = ETHASH_IO_FAIL;
@@ -53,14 +56,26 @@ enum ethash_io_rc ethash_io_prepare(char const *dirname, ethash_h256_t seedhash)
 	}
 
 	// try to open the file
-	FILE *f = ethash_fopen(tmpfile, "rb");
+	FILE *f = ethash_fopen(tmpfile, "rb+");
 	if (!f) {
 		// file does not exist, will need to be created
-		ret = ETHASH_IO_MEMO_MISMATCH;
+		f = ethash_fopen(tmpfile, "wb+");
+		if (!f) {
+			goto free_memo;
+		}
+		// make sure it's of the proper size
+		if (fseek(f, file_size - 1, SEEK_SET) != 0) {
+			fclose(f);
 			goto free_memo;
 		}
+		fputc('\n', f);
+		fflush(f);
+		ret = ETHASH_IO_MEMO_MISMATCH;
+		goto set_file;
+	}
 
 	ret = ETHASH_IO_MEMO_MATCH;
+set_file:
 	*output_file = f;
 free_memo:
 	free(tmpfile);

mmap.h

@@ -0,0 +1,28 @@
+/*
+  This file is part of ethash.
+
+  ethash is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  ethash is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with ethash.  If not, see <http://www.gnu.org/licenses/>.
+*/
+/** @file mmap.h
+ * @author Lefteris Karapetsas <lefteris@ethdev.com>
+ * @date 2015
+ */
+#pragma once
+#if defined(__MINGW32__) || defined(_WIN32)
+void *mmap(void *start, size_t length, int prot, int flags, int fd, off_t offset);
+#else
+#include <sys/mman.h>
+#endif
+
+

mmap_win32.c

@@ -0,0 +1,101 @@
+/* mmap() replacement for Windows
+ *
+ * Author: Mike Frysinger <vapier@gentoo.org>
+ * Placed into the public domain
+ */
+
+/* References:
+ * CreateFileMapping: http://msdn.microsoft.com/en-us/library/aa366537(VS.85).aspx
+ * CloseHandle:       http://msdn.microsoft.com/en-us/library/ms724211(VS.85).aspx
+ * MapViewOfFile:     http://msdn.microsoft.com/en-us/library/aa366761(VS.85).aspx
+ * UnmapViewOfFile:   http://msdn.microsoft.com/en-us/library/aa366882(VS.85).aspx
+ */
+
+#include <io.h>
+#include <windows.h>
+#include <sys/types.h>
+#include "mmap.h"
+
+#define PROT_READ     0x1
+#define PROT_WRITE    0x2
+/* This flag is only available in WinXP+ */
+#ifdef FILE_MAP_EXECUTE
+#define PROT_EXEC     0x4
+#else
+#define PROT_EXEC        0x0
+#define FILE_MAP_EXECUTE 0
+#endif
+
+#define MAP_SHARED    0x01
+#define MAP_PRIVATE   0x02
+#define MAP_ANONYMOUS 0x20
+#define MAP_ANON      MAP_ANONYMOUS
+#define MAP_FAILED    ((void *) -1)
+
+#ifdef __USE_FILE_OFFSET64
+# define DWORD_HI(x) (x >> 32)
+# define DWORD_LO(x) ((x) & 0xffffffff)
+#else
+# define DWORD_HI(x) (0)
+# define DWORD_LO(x) (x)
+#endif
+
+void *mmap(void *start, size_t length, int prot, int flags, int fd, off_t offset)
+{
+	if (prot & ~(PROT_READ | PROT_WRITE | PROT_EXEC))
+		return MAP_FAILED;
+	if (fd == -1) {
+		if (!(flags & MAP_ANON) || offset)
+			return MAP_FAILED;
+	} else if (flags & MAP_ANON)
+		return MAP_FAILED;
+
+	DWORD flProtect;
+	if (prot & PROT_WRITE) {
+		if (prot & PROT_EXEC)
+			flProtect = PAGE_EXECUTE_READWRITE;
+		else
+			flProtect = PAGE_READWRITE;
+	} else if (prot & PROT_EXEC) {
+		if (prot & PROT_READ)
+			flProtect = PAGE_EXECUTE_READ;
+		else if (prot & PROT_EXEC)
+			flProtect = PAGE_EXECUTE;
+	} else
+		flProtect = PAGE_READONLY;
+
+	off_t end = length + offset;
+	HANDLE mmap_fd, h;
+	if (fd == -1)
+		mmap_fd = INVALID_HANDLE_VALUE;
+	else
+		mmap_fd = (HANDLE)_get_osfhandle(fd);
+	h = CreateFileMapping(mmap_fd, NULL, flProtect, DWORD_HI(end), DWORD_LO(end), NULL);
+	if (h == NULL)
+		return MAP_FAILED;
+
+	DWORD dwDesiredAccess;
+	if (prot & PROT_WRITE)
+		dwDesiredAccess = FILE_MAP_WRITE;
+	else
+		dwDesiredAccess = FILE_MAP_READ;
+	if (prot & PROT_EXEC)
+		dwDesiredAccess |= FILE_MAP_EXECUTE;
+	if (flags & MAP_PRIVATE)
+		dwDesiredAccess |= FILE_MAP_COPY;
+	void *ret = MapViewOfFile(h, dwDesiredAccess, DWORD_HI(offset), DWORD_LO(offset), length);
+	if (ret == NULL) {
+		CloseHandle(h);
+		ret = MAP_FAILED;
+	}
+	return ret;
+}
+
+static void munmap(void *addr, size_t length)
+{
+	UnmapViewOfFile(addr);
+	/* ruh-ro, we leaked handle from CreateFileMapping() ... */
+}
+
+#undef DWORD_HI
+#undef DWORD_LO