From 887ce3b4b7f0457dc70f85fa16c64ee22a494d52 Mon Sep 17 00:00:00 2001 From: Thomas Munro Date: Sat, 23 Jul 2022 23:24:14 +1200 Subject: [PATCH 12/13] Simplify replacement code for preadv and pwritev. preadv and pwritev are not standardized by POSIX, but all targeted Unix systems have them except for Solaris (illumos has them since 2015). We had two replacement implementations, one based on lseek() + readv()/writev() and another based on a simple loop. The former was used by Solaris only, and the latter by Windows only. Supporting the extra path only for Solaris, at the cost of having a pg_preadv/pg_pwritev that could never be used in a multi-threaded program accessing the same file descriptor from two threads does not sound like a good trade. Drop the readv()/writev() variant, and also the pg_ prefix, now that the file position portability hazard is gone. --- configure | 2 +- configure.ac | 2 -- src/backend/storage/file/fd.c | 4 ++-- src/include/pg_config.h.in | 6 ------ src/include/port/pg_iovec.h | 12 ++++-------- src/port/preadv.c | 13 +------------ src/port/pwritev.c | 13 +------------ src/tools/msvc/Solution.pm | 2 -- 8 files changed, 9 insertions(+), 45 deletions(-) diff --git a/configure b/configure index 3c7ae744ca..531161182a 100755 --- a/configure +++ b/configure @@ -16039,7 +16039,7 @@ fi LIBS_including_readline="$LIBS" LIBS=`echo "$LIBS" | sed -e 's/-ledit//g' -e 's/-lreadline//g'` -for ac_func in backtrace_symbols copyfile fdatasync getifaddrs getpeerucred inet_pton kqueue mbstowcs_l memset_s posix_fallocate ppoll pthread_is_threaded_np readv setproctitle setproctitle_fast strchrnul strsignal syncfs sync_file_range uselocale wcstombs_l writev +for ac_func in backtrace_symbols copyfile fdatasync getifaddrs getpeerucred inet_pton kqueue mbstowcs_l memset_s posix_fallocate ppoll pthread_is_threaded_np setproctitle setproctitle_fast strchrnul strsignal syncfs sync_file_range uselocale wcstombs_l do : as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh` ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var" diff --git a/configure.ac b/configure.ac index bc8534717d..56ec5a0b08 100644 --- a/configure.ac +++ b/configure.ac @@ -1802,7 +1802,6 @@ AC_CHECK_FUNCS(m4_normalize([ posix_fallocate ppoll pthread_is_threaded_np - readv setproctitle setproctitle_fast strchrnul @@ -1811,7 +1810,6 @@ AC_CHECK_FUNCS(m4_normalize([ sync_file_range uselocale wcstombs_l - writev ])) # These typically are compiler builtins, for which AC_CHECK_FUNCS fails. diff --git a/src/backend/storage/file/fd.c b/src/backend/storage/file/fd.c index 71e7f2e143..7d72b842c3 100644 --- a/src/backend/storage/file/fd.c +++ b/src/backend/storage/file/fd.c @@ -3762,7 +3762,7 @@ data_sync_elevel(int elevel) } /* - * A convenience wrapper for pg_pwritev() that retries on partial write. If an + * A convenience wrapper for pwritev() that retries on partial write. If an * error is returned, it is unspecified how much has been written. */ ssize_t @@ -3782,7 +3782,7 @@ pg_pwritev_with_retry(int fd, const struct iovec *iov, int iovcnt, off_t offset) for (;;) { /* Write as much as we can. */ - part = pg_pwritev(fd, iov, iovcnt, offset); + part = pwritev(fd, iov, iovcnt, offset); if (part < 0) return -1; diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in index e8633878d2..f7a7b8116c 100644 --- a/src/include/pg_config.h.in +++ b/src/include/pg_config.h.in @@ -417,9 +417,6 @@ /* Define to 1 if you have the header file. */ #undef HAVE_READLINE_READLINE_H -/* Define to 1 if you have the `readv' function. */ -#undef HAVE_READV - /* Define to 1 if you have the `rl_completion_matches' function. */ #undef HAVE_RL_COMPLETION_MATCHES @@ -648,9 +645,6 @@ /* Define to 1 if you have the header file. */ #undef HAVE_WINLDAP_H -/* Define to 1 if you have the `writev' function. */ -#undef HAVE_WRITEV - /* Define to 1 if you have the `X509_get_signature_nid' function. */ #undef HAVE_X509_GET_SIGNATURE_NID diff --git a/src/include/port/pg_iovec.h b/src/include/port/pg_iovec.h index f0b1a71bcb..f0a50c0e01 100644 --- a/src/include/port/pg_iovec.h +++ b/src/include/port/pg_iovec.h @@ -39,16 +39,12 @@ struct iovec /* Define a reasonable maximum that is safe to use on the stack. */ #define PG_IOV_MAX Min(IOV_MAX, 32) -#if HAVE_DECL_PREADV -#define pg_preadv preadv -#else -extern ssize_t pg_preadv(int fd, const struct iovec *iov, int iovcnt, off_t offset); +#if !HAVE_DECL_PREADV +extern ssize_t preadv(int fd, const struct iovec *iov, int iovcnt, off_t offset); #endif -#if HAVE_DECL_PWRITEV -#define pg_pwritev pwritev -#else -extern ssize_t pg_pwritev(int fd, const struct iovec *iov, int iovcnt, off_t offset); +#if !HAVE_DECL_PWRITEV +extern ssize_t pwritev(int fd, const struct iovec *iov, int iovcnt, off_t offset); #endif #endif /* PG_IOVEC_H */ diff --git a/src/port/preadv.c b/src/port/preadv.c index aa7537503f..0aaf99222f 100644 --- a/src/port/preadv.c +++ b/src/port/preadv.c @@ -8,9 +8,6 @@ * IDENTIFICATION * src/port/preadv.c * - * Note that this implementation changes the current file position, unlike - * the POSIX-like function, so we use the name pg_preadv(). - * *------------------------------------------------------------------------- */ @@ -26,15 +23,8 @@ #include "port/pg_iovec.h" ssize_t -pg_preadv(int fd, const struct iovec *iov, int iovcnt, off_t offset) +preadv(int fd, const struct iovec *iov, int iovcnt, off_t offset) { -#ifdef HAVE_READV - if (iovcnt == 1) - return pread(fd, iov[0].iov_base, iov[0].iov_len, offset); - if (lseek(fd, offset, SEEK_SET) < 0) - return -1; - return readv(fd, iov, iovcnt); -#else ssize_t sum = 0; ssize_t part; @@ -54,5 +44,4 @@ pg_preadv(int fd, const struct iovec *iov, int iovcnt, off_t offset) return sum; } return sum; -#endif } diff --git a/src/port/pwritev.c b/src/port/pwritev.c index cb7421381e..a0fa4b8edd 100644 --- a/src/port/pwritev.c +++ b/src/port/pwritev.c @@ -8,9 +8,6 @@ * IDENTIFICATION * src/port/pwritev.c * - * Note that this implementation changes the current file position, unlike - * the POSIX-like function, so we use the name pg_pwritev(). - * *------------------------------------------------------------------------- */ @@ -26,15 +23,8 @@ #include "port/pg_iovec.h" ssize_t -pg_pwritev(int fd, const struct iovec *iov, int iovcnt, off_t offset) +pwritev(int fd, const struct iovec *iov, int iovcnt, off_t offset) { -#ifdef HAVE_WRITEV - if (iovcnt == 1) - return pwrite(fd, iov[0].iov_base, iov[0].iov_len, offset); - if (lseek(fd, offset, SEEK_SET) < 0) - return -1; - return writev(fd, iov, iovcnt); -#else ssize_t sum = 0; ssize_t part; @@ -54,5 +44,4 @@ pg_pwritev(int fd, const struct iovec *iov, int iovcnt, off_t offset) return sum; } return sum; -#endif } diff --git a/src/tools/msvc/Solution.pm b/src/tools/msvc/Solution.pm index 811cfe1ff3..a4cebdcf96 100644 --- a/src/tools/msvc/Solution.pm +++ b/src/tools/msvc/Solution.pm @@ -333,7 +333,6 @@ sub GenerateFiles HAVE_READLINE_H => undef, HAVE_READLINE_HISTORY_H => undef, HAVE_READLINE_READLINE_H => undef, - HAVE_READV => undef, HAVE_RL_COMPLETION_MATCHES => undef, HAVE_RL_COMPLETION_SUPPRESS_QUOTE => undef, HAVE_RL_FILENAME_COMPLETION_FUNCTION => undef, @@ -409,7 +408,6 @@ sub GenerateFiles HAVE_WINLDAP_H => undef, HAVE_WCSTOMBS_L => 1, HAVE_VISIBILITY_ATTRIBUTE => undef, - HAVE_WRITEV => undef, HAVE_X509_GET_SIGNATURE_NID => 1, HAVE_X86_64_POPCNTQ => undef, HAVE__BOOL => undef, -- 2.30.2