thodg/libgit2/src/buffer.c

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• Hash : afeecf4f
  Author :
  Date : 2011-07-09T02:10:46
  

  odb: Direct writes are back
  
  DIRECT WRITES ARE BACK AND FASTER THAN EVER. The streaming writer to the
  ODB was an overkill for the smaller objects like Commit and Tags; most
  of the streaming logic was taking too long.
  
  This commit makes Commits, Tags and Trees to be built-up in memory, and
  then written to disk in 2 pushes (header + data), instead of streaming
  everything.
  
  This is *always* faster, even for big files (since the git_filebuf class
  still does streaming writes when the memory cache overflows). This is
  also a gazillion lines of code smaller, because we don't have to
  precompute the final size of the object before starting the stream (this
  was kind of defeating the point of streaming, anyway).
  
  Blobs are still written with full streaming instead of loading them in
  memory, since this is still the fastest way.
  
  A new `git_buf` class has been added. It's missing some features, but
  it'll get there.
  

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• src/buffer.c

• #include "buffer.h"
  #include "posix.h"
  #include <stdarg.h>
  
  #define ENSURE_SIZE(b, d) \
  	if ((ssize_t)(d) >= buf->asize && git_buf_grow(b, (d)) < GIT_SUCCESS)\
  		return;
  
  int git_buf_grow(git_buf *buf, size_t target_size)
  {
  	char *new_ptr;
  
  	if (buf->asize < 0)
  		return GIT_ENOMEM;
  
  	if (buf->asize == 0)
  		buf->asize = target_size;
  
  	/* grow the buffer size by 1.5, until it's big enough
  	 * to fit our target size */
  	while (buf->asize < (int)target_size)
  		buf->asize = (buf->asize << 1) - (buf->asize >> 1);
  
  	new_ptr = git__realloc(buf->ptr, buf->asize);
  	if (!new_ptr) {
  		buf->asize = -1;
  		return GIT_ENOMEM;
  	}
  
  	buf->ptr = new_ptr;
  	return GIT_SUCCESS;
  }
  
  int git_buf_oom(const git_buf *buf)
  {
  	return (buf->asize < 0);
  }
  
  void git_buf_putc(git_buf *buf, char c)
  {
  	ENSURE_SIZE(buf, buf->size + 1);
  	buf->ptr[buf->size++] = c;
  }
  
  void git_buf_put(git_buf *buf, const char *data, size_t len)
  {
  	ENSURE_SIZE(buf, buf->size + len);
  	memcpy(buf->ptr + buf->size, data, len);
  	buf->size += len;
  }
  
  void git_buf_puts(git_buf *buf, const char *string)
  {
  	git_buf_put(buf, string, strlen(string));
  }
  
  void git_buf_printf(git_buf *buf, const char *format, ...)
  {
  	int len;
  	va_list arglist;
  
  	ENSURE_SIZE(buf, buf->size + 1);
  
  	while (1) {
  		va_start(arglist, format);
  		len = p_vsnprintf(buf->ptr + buf->size, buf->asize - buf->size, format, arglist);
  		va_end(arglist);
  
  		if (len < 0) {
  			buf->asize = -1;
  			return;
  		}
  
  		if (len + 1 <= buf->asize - buf->size) {
  			buf->size += len;
  			return;
  		}
  
  		ENSURE_SIZE(buf, buf->size + len + 1);
  	}
  }
  
  const char *git_buf_cstr(git_buf *buf)
  {
  	if (buf->size + 1 >= buf->asize && git_buf_grow(buf, buf->size + 1) < GIT_SUCCESS)
  		return NULL;
  
  	buf->ptr[buf->size] = '\0';
  	return buf->ptr;
  }
  
  void git_buf_free(git_buf *buf)
  {
  	free(buf->ptr);
  }
  

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