2019独角兽企业重金招聘Python工程师标准>>> 
#ifndef __SEAL_FILEPOOL_H__
#define __SEAL_FILEPOOL_H__
#include "error.h"
#include "hash.h"
#include "macro.h"
#include "path.h"
#include "threads.h"
#include
#include
namespace sea {
namespace posix {
#include
}
class file_pool {
private:
static constexpr int FGR = 1;
static constexpr int FGW = 2;
static constexpr int FGA = 4;
static constexpr int FGP = 8;
static constexpr int FGB = 16;
struct opened {
int flag;
FILE *file;
int rc;
};
sea::hash_map _opened;
spin_lock _lock;
file_pool() = default;
~file_pool() noexcept {
for (auto &p : _opened) {
fclose(p.second.file);
}
}
seal_macro_non_copy(file_pool)
static file_pool &instance() {
static file_pool fp;
return fp;
}
FILE *open_impl(const char *p, const char *m) {
if ( !p || *p == '\0' || strcmp(p, "null") == 0 ) {
p = "/dev/null";
} else if ( strcmp(p, "stdin") == 0 ) {
return stdin;
} else if ( strcmp(p, "stdout") == 0 ) {
return stdout;
} else if ( strcmp(p, "stderr") == 0 ) {
return stderr;
}
int fg = 0;
fg |= strchr(m, 'r') ? FGR : 0;
fg |= strchr(m, 'w') ? FGW : 0;
fg |= strchr(m, 'a') ? FGA : 0;
fg |= strchr(m, '+') ? FGP : 0;
fg |= strchr(m, 'b') ? FGB : 0;
if ( strcmp(p, "-") == 0 ) {
if ( (fg & (FGW | FGA | FGP)) == 0 ) {
return stdin;
} else if ( (fg & (FGR | FGP)) == 0 ) {
return stdout;
}
}
using namespace posix;
struct stat sb;
int rt = stat(p, &sb);
std::lock_guard lg(_lock);
if ( rt != 0 || _opened.count(sb.st_ino) == 0 ) {
FILE *f = fopen(p, m);
if ( f == nullptr ) {
raise(cannot_open(p, m));
} else {
size_t n = inode(f);
_opened.insert({n, opened{fg, f, 1}});
}
return f;
} else {
auto i = _opened.find(sb.st_ino);
if ( i->second.flag == fg ) {
++i->second.rc;
return i->second.file;
}
raise(cannot_open(p, m));
return nullptr;
}
}
void close_impl(FILE *f) {
if ( f == stdin || f == stdout || f == stderr ) {
return;
}
size_t n = inode(f);
std::lock_guard lg(_lock);
auto i = _opened.find(n);
if ( i != _opened.end() && --i->second.rc == 0 ) {
fclose(i->second.file);
_opened.erase(i);
}
}
size_t inode(FILE *f) {
using namespace posix;
struct stat sb;
fstat(fileno(f), &sb);
return sb.st_ino;
}
static file_error cannot_open(const char *p, const char *m) {
char s[1024];
snprintf(s, 1024, "cannot open file \"%s\" with flag \"%s\"\n", p, m);
return file_error(s);
}
public:
static FILE *open(const char *p, const char *m) {
return instance().open_impl(p, m);
}
static FILE *open(const std::string &p, const std::string &m) {
return open(p.data(), m.data());
}
static void close(FILE *f) {
instance().close_impl(f);
}
};
}
#endif // __SEAL_FILEPOOL_H__ /src/sealib/filepool.h文件描述了程序对于文件处理的一些函数，如open(),close()，基本上实现了文件的所有状态判断与操作。其中static constexpr定义了一些静态常量数据。程序中运用了一些线程的知识。The design of lock_guard is quite straight-forward. Basically, lock_guard requires the resource it can lock to have two methods, lock() and unlock(), once your resource class has these two methods, it can be used with lock_guard. lock_guard will call lock() in constructor and call unlock() in destructor.
其中文件file的定义位于/usr/include/stdio.h这个头文件中。
/* The opaque type of streams. This is the definition used elsewhere. */
typedef struct _IO_FILE FILE;
__END_NAMESPACE_STD
#if defined __USE_LARGEFILE64 || defined __USE_SVID || defined __USE_POSIX \
|| defined __USE_BSD || defined __USE_ISOC99 || defined __USE_XOPEN \
|| defined __USE_POSIX2
__USING_NAMESPACE_STD(FILE)
#endif