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Diffstat (limited to 'ext/sleepy_penguin/splice.c')
| -rw-r--r-- | ext/sleepy_penguin/splice.c | 376 |
1 files changed, 376 insertions, 0 deletions
diff --git a/ext/sleepy_penguin/splice.c b/ext/sleepy_penguin/splice.c new file mode 100644 index 0000000..d2f9206 --- /dev/null +++ b/ext/sleepy_penguin/splice.c @@ -0,0 +1,376 @@ +#include "sleepy_penguin.h" +#ifdef HAVE_SPLICE +#include <errno.h> +#include <fcntl.h> +#include <assert.h> +#include <sys/uio.h> +#include <limits.h> +#include <unistd.h> + +static VALUE sym_EAGAIN; + +#ifndef F_LINUX_SPECIFIC_BASE +# define F_LINUX_SPECIFIC_BASE 1024 +#endif + +#ifndef F_GETPIPE_SZ +# define F_SETPIPE_SZ (F_LINUX_SPECIFIC_BASE + 7) +# define F_GETPIPE_SZ (F_LINUX_SPECIFIC_BASE + 8) +#endif + +#ifndef SSIZET2NUM +# define SSIZET2NUM(x) LONG2NUM(x) +#endif +#ifndef NUM2SIZET +# define NUM2SIZET(x) NUM2ULONG(x) +#endif + +static int check_fileno(VALUE io) +{ + int saved_errno = errno; + int fd = rb_sp_fileno(io); + errno = saved_errno; + return fd; +} + +#if defined(HAVE_RB_THREAD_CALL_WITHOUT_GVL) && defined(HAVE_RUBY_THREAD_H) +/* Ruby 2.0+ */ +# include <ruby/thread.h> +# define WITHOUT_GVL(fn,a,ubf,b) \ + rb_thread_call_without_gvl((fn),(a),(ubf),(b)) +#elif defined(HAVE_RB_THREAD_BLOCKING_REGION) +typedef VALUE (*my_blocking_fn_t)(void*); +# define WITHOUT_GVL(fn,a,ubf,b) \ + rb_thread_blocking_region((my_blocking_fn_t)(fn),(a),(ubf),(b)) + +#else /* Ruby 1.8 */ +/* partial emulation of the 1.9 rb_thread_blocking_region under 1.8 */ +# include <rubysig.h> +# define RUBY_UBF_IO ((rb_unblock_function_t *)-1) +typedef void rb_unblock_function_t(void *); +typedef void * rb_blocking_function_t(void *); +static void * WITHOUT_GVL(rb_blocking_function_t *func, void *data1, + rb_unblock_function_t *ubf, void *data2) +{ + void *rv; + + assert(RUBY_UBF_IO == ubf && "RUBY_UBF_IO required for emulation"); + + TRAP_BEG; + rv = func(data1); + TRAP_END; + + return rv; +} +#endif /* ! HAVE_RB_THREAD_BLOCKING_REGION */ + +#define IO_RUN(fn,data) WITHOUT_GVL((fn),(data),RUBY_UBF_IO,0) + +struct splice_args { + int fd_in; + int fd_out; + off_t *off_in; + off_t *off_out; + size_t len; + unsigned flags; +}; + +static void *nogvl_splice(void *ptr) +{ + struct splice_args *a = ptr; + + return (void *)splice(a->fd_in, a->off_in, a->fd_out, a->off_out, + a->len, a->flags); +} + +static ssize_t do_splice(int argc, VALUE *argv, unsigned dflags) +{ + off_t i = 0, o = 0; + VALUE io_in, off_in, io_out, off_out, len, flags; + struct splice_args a; + ssize_t bytes; + ssize_t total = 0; + + rb_scan_args(argc, argv, "51", + &io_in, &off_in, &io_out, &off_out, &len, &flags); + + a.off_in = NIL_P(off_in) ? NULL : (i = NUM2OFFT(off_in), &i); + a.off_out = NIL_P(off_out) ? NULL : (o = NUM2OFFT(off_out), &o); + a.len = NUM2SIZET(len); + a.flags = NIL_P(flags) ? dflags : NUM2UINT(flags) | dflags; + + for (;;) { + a.fd_in = check_fileno(io_in); + a.fd_out = check_fileno(io_out); + bytes = (ssize_t)IO_RUN(nogvl_splice, &a); + if (bytes < 0) { + if (errno == EINTR) + continue; + if (total > 0) + return total; + return bytes; + } else if (bytes == 0) { + break; + } else { + return bytes; + } + } + + return total; +} + +/* + * call-seq: + * SleepyPenguin.splice(io_in, off_in, io_out, off_out, len) => integer + * SleepyPenguin.splice(io_in, off_in, io_out, off_out, len, flags) => integer + * + * Splice +len+ bytes from/to a pipe. Either +io_in+ or +io_out+ + * MUST be a pipe. +io_in+ and +io_out+ may BOTH be pipes as of + * Linux 2.6.31 or later. + * + * +off_in+ and +off_out+ if non-nil may be used to + * specify an offset for the non-pipe file descriptor. + * + * +flags+ defaults to zero if unspecified. + * +flags+ may be a bitmask of the following flags: + * + * * SleepyPenguin::F_MOVE + * * SleepyPenguin::F_NONBLOCK + * * SleepyPenguin::F_MORE + * + * Returns the number of bytes spliced. + * Raises EOFError when +io_in+ has reached end of file. + * Raises Errno::EAGAIN if the SleepyPenguin::F_NONBLOCK flag is set + * and the pipe has no data to read from or space to write to. May + * also raise Errno::EAGAIN if the non-pipe descriptor has no data + * to read from or space to write to. + * + * As splice never exposes buffers to userspace, it will not take + * into account userspace buffering done by Ruby or stdio. It is + * also not subject to encoding/decoding filters under Ruby 1.9. + * + * Consider using SleepyPenguin.trysplice if +io_out+ is a pipe or if you are using + * non-blocking I/O on both descriptors as it avoids the cost of raising + * common Errno::EAGAIN exceptions. + * + * See manpage for full documentation: + * http://kernel.org/doc/man-pages/online/pages/man2/splice.2.html + */ +static VALUE my_splice(int argc, VALUE *argv, VALUE self) +{ + ssize_t n = do_splice(argc, argv, 0); + + if (n == 0) + rb_eof_error(); + if (n < 0) + rb_sys_fail("splice"); + return SSIZET2NUM(n); +} + +/* + * call-seq: + * SleepyPenguin.trysplice(io_in, off_in, io_out, off_out, len) => integer + * SleepyPenguin.trysplice(io_in, off_in, io_out, off_out, len, flags) => integer + * + * Exactly like SleepyPenguin.splice, except +:EAGAIN+ is returned when either + * the read or write end would block instead of raising Errno::EAGAIN. + * + * SleepyPenguin::F_NONBLOCK is always passed for the pipe descriptor, + * but this can still block if the non-pipe descriptor is blocking. + * + * See SleepyPenguin.splice documentation for more details. + * + * This method is recommended whenever +io_out+ is a pipe. + */ +static VALUE trysplice(int argc, VALUE *argv, VALUE self) +{ + ssize_t n = do_splice(argc, argv, SPLICE_F_NONBLOCK); + + if (n == 0) + return Qnil; + if (n < 0) { + if (errno == EAGAIN) + return sym_EAGAIN; + rb_sys_fail("splice"); + } + return SSIZET2NUM(n); +} + +struct tee_args { + int fd_in; + int fd_out; + size_t len; + unsigned flags; +}; + +/* runs without GVL */ +static void *nogvl_tee(void *ptr) +{ + struct tee_args *a = ptr; + + return (void *)tee(a->fd_in, a->fd_out, a->len, a->flags); +} + +static ssize_t do_tee(int argc, VALUE *argv, unsigned dflags) +{ + VALUE io_in, io_out, len, flags; + struct tee_args a; + ssize_t bytes; + ssize_t total = 0; + + rb_scan_args(argc, argv, "31", &io_in, &io_out, &len, &flags); + a.len = (size_t)NUM2SIZET(len); + a.flags = NIL_P(flags) ? dflags : NUM2UINT(flags) | dflags; + + for (;;) { + a.fd_in = check_fileno(io_in); + a.fd_out = check_fileno(io_out); + bytes = (ssize_t)IO_RUN(nogvl_tee, &a); + if (bytes < 0) { + if (errno == EINTR) + continue; + if (total > 0) + return total; + return bytes; + } else if (bytes == 0) { + break; + } else { + return bytes; + } + } + + return total; +} + +/* + * call-seq: + * SleepyPenguin.tee(io_in, io_out, len) => integer + * SleepyPenguin.tee(io_in, io_out, len, flags) => integer + * + * Copies up to +len+ bytes of data from +io_in+ to +io_out+. +io_in+ + * and +io_out+ must both refer to pipe descriptors. +io_in+ and +io_out+ + * may not be endpoints of the same pipe. + * + * +flags+ may be zero (the default) or a combination of: + * * SleepyPenguin::F_NONBLOCK + * + * Other splice-related flags are currently unimplemented or have no effect. + * + * Returns the number of bytes duplicated if successful. + * Raises EOFError when +io_in+ is closed and emptied. + * Raises Errno::EAGAIN when +io_in+ is empty and/or +io_out+ is full + * and +flags+ contains SleepyPenguin::F_NONBLOCK + * + * Consider using SleepyPenguin.trytee if you are using + * SleepyPenguin::F_NONBLOCK as it avoids the cost of raising + * common Errno::EAGAIN exceptions. + * + * See manpage for full documentation: + * http://kernel.org/doc/man-pages/online/pages/man2/tee.2.html + */ +static VALUE my_tee(int argc, VALUE *argv, VALUE self) +{ + ssize_t n = do_tee(argc, argv, 0); + + if (n == 0) + rb_eof_error(); + if (n < 0) + rb_sys_fail("tee"); + + return SSIZET2NUM(n); +} + +/* + * call-seq: + * SleepyPenguin.trytee(io_in, io_out, len) => integer + * SleepyPenguin.trytee(io_in, io_out, len, flags) => integer + * + * Exactly like SleepyPenguin.tee, except +:EAGAIN+ is returned when either + * the read or write end would block instead of raising Errno::EAGAIN. + * + * SleepyPenguin::F_NONBLOCK is always passed for the pipe descriptor, + * but this can still block if the non-pipe descriptor is blocking. + * + * See SleepyPenguin.tee documentation for more details. + */ +static VALUE trytee(int argc, VALUE *argv, VALUE self) +{ + ssize_t n = do_tee(argc, argv, SPLICE_F_NONBLOCK); + + if (n == 0) + return Qnil; + if (n < 0) { + if (errno == EAGAIN) + return sym_EAGAIN; + rb_sys_fail("tee"); + } + + return SSIZET2NUM(n); +} + +void sleepy_penguin_init_splice(void) +{ + VALUE mod = rb_define_module("SleepyPenguin"); + rb_define_singleton_method(mod, "splice", my_splice, -1); + rb_define_singleton_method(mod, "trysplice", trysplice, -1); + rb_define_singleton_method(mod, "tee", my_tee, -1); + rb_define_singleton_method(mod, "trytee", trytee, -1); + + /* + * Attempt to move pages instead of copying. This is only a hint + * and support for it was removed in Linux 2.6.21. It will be + * re-added for FUSE filesystems only in Linux 2.6.35. + */ + rb_define_const(mod, "F_MOVE", UINT2NUM(SPLICE_F_MOVE)); + + /* + * Do not block on pipe I/O. This flag only affects the pipe(s) + * being spliced from/to and has no effect on the non-pipe + * descriptor (which requires non-blocking operation to be set + * explicitly). + * + * The non-blocking flag (O_NONBLOCK) on the pipe descriptors + * themselves are ignored by this family of functions, and + * using this flag is the only way to get non-blocking operation + * out of them. + * + * It is highly recommended this flag be set + * (or SleepyPenguin.trysplice used) + * whenever splicing from a socket into a pipe unless there is + * another (native) thread or process doing a blocking read on that + * pipe. Otherwise it is possible to block a single-threaded process + * if the socket buffers are larger than the pipe buffers. + */ + rb_define_const(mod, "F_NONBLOCK", UINT2NUM(SPLICE_F_NONBLOCK)); + + /* + * Indicate that there may be more data coming into the outbound + * descriptor. This can allow the kernel to avoid sending partial + * frames from sockets. Currently only used with splice. + */ + rb_define_const(mod, "F_MORE", UINT2NUM(SPLICE_F_MORE)); + + /* + * The maximum size of an atomic write to a pipe + * POSIX requires this to be at least 512 bytes. + * Under Linux, this is 4096 bytes. + */ + rb_define_const(mod, "PIPE_BUF", UINT2NUM(PIPE_BUF)); + + /* + * fcntl() command constant used to return the size of a pipe. + * This constant is only defined when running Linux 2.6.35 + * or later. For convenience, use IO#pipe_size instead. + */ + rb_define_const(mod, "F_GETPIPE_SZ", UINT2NUM(F_GETPIPE_SZ)); + + /* + * fcntl() command constant used to set the size of a pipe. + * This constant is only defined when running Linux 2.6.35 + * or later. For convenience, use IO#pipe_size= instead. + */ + rb_define_const(mod, "F_SETPIPE_SZ", UINT2NUM(F_SETPIPE_SZ)); + + sym_EAGAIN = ID2SYM(rb_intern("EAGAIN")); +} +#endif |