Add zpq_buffered_rx() to ZpqStream #1
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knizhnik
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knizhnik
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usernamedt
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Due to how pg_size_pretty(bigint) was implemented, it's possible that when given a negative number of bytes that the returning value would not match the equivalent positive return value when given the equivalent positive number of bytes. This was due to two separate issues. 1. The function used bit shifting to convert the number of bytes into larger units. The rounding performed by bit shifting is not the same as dividing. For example -3 >> 1 = -2, but -3 / 2 = -1. These two operations are only equivalent with positive numbers. 2. The half_rounded() macro rounded towards positive infinity. This meant that negative numbers rounded towards zero and positive numbers rounded away from zero. Here we fix postgrespro#1 by dividing the values instead of bit shifting. We fix postgrespro#2 by adjusting the half_rounded macro always to round away from zero. Additionally, adjust the pg_size_pretty(numeric) function to be more explicit that it's using division rather than bit shifting. A casual observer might have believed bit shifting was used due to a static function being named numeric_shift_right. However, that function was calculating the divisor from the number of bits and performed division. Here we make that more clear. This change is just cosmetic and does not affect the return value of the numeric version of the function. Here we also add a set of regression tests both versions of pg_size_pretty() which test the values directly before and after the function switches to the next unit. This bug was introduced in 8a1fab3. Prior to that negative values were always displayed in bytes. Author: Dean Rasheed, David Rowley Discussion: https://postgr.es/m/CAEZATCXnNW4HsmZnxhfezR5FuiGgp+mkY4AzcL5eRGO4fuadWg@mail.gmail.com Backpatch-through: 9.6, where the bug was introduced.
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Currently the pc files use hard coded paths for "includedir" and
"libdir."
Example:
Cflags: -I/usr/include
Libs: -L/usr/lib -lpq
This is not very fortunate when cross compiling inside a buildroot,
where the includes and libs are inside a staging directory, because
this introduces host paths into the build:
checking for pkg-config... /builder/shared-workdir/build/sdk/staging_dir/host/bin/pkg-config
checking for PostgreSQL libraries via pkg_config... -L/usr/lib <----
This commit addresses this by doing the following two things:
1. Instead of hard coding the paths in "Cflags" and "Libs"
"${includedir}" and "${libdir}" are used. Note: these variables
can be overriden on the pkg-config command line
("--define-variable=libdir=/some/path").
2. Add the variables "prefix" and "exec_prefix". If "includedir"
and/or "libdir" are using these then construct them accordingly.
This is done because buildroots (for instance OpenWrt) tend to
rename the real pkg-config and call it indirectly from a script
that sets "prefix", "exec_prefix" and "bindir", like so:
pkg-config.real --define-variable=prefix=${STAGING_PREFIX} \
--define-variable=exec_prefix=${STAGING_PREFIX} \
--define-variable=bindir=${STAGING_PREFIX}/bin $@
Example postgrespro#1: user calls ./configure with "--libdir=/some/lib" and
"--includedir=/some/include":
prefix=/usr/local/pgsql
exec_prefix=${prefix}
libdir=/some/lib
includedir=/some/include
Name: libpq
Description: PostgreSQL libpq library
Url: http://www.postgresql.org/
Version: 12.1
Requires:
Requires.private:
Cflags: -I${includedir}
Libs: -L${libdir} -lpq
Libs.private: -lcrypt -lm
Example postgrespro#2: user calls ./configure with no arguments:
prefix=/usr/local/pgsql
exec_prefix=${prefix}
libdir=${exec_prefix}/lib
includedir=${prefix}/include
Name: libpq
Description: PostgreSQL libpq library
Url: http://www.postgresql.org/
Version: 12.1
Requires:
Requires.private:
Cflags: -I${includedir}
Libs: -L${libdir} -lpq
Libs.private: -lcrypt -lm
Like this the paths can be forced into the staging directory when
using a buildroot setup:
checking for pkg-config... /home/sk/tmp/openwrt/staging_dir/host/bin/pkg-config
checking for PostgreSQL libraries via pkg_config... -L/home/sk/tmp/openwrt/staging_dir/target-mips_24kc_musl/usr/lib
Author: Sebastian Kemper <sebastian_ml@gmx.net>
Co-authored-by: Peter Eisentraut <peter.eisentraut@enterprisedb.com>
Discussion: https://www.postgresql.org/message-id/flat/20200305213827.GA25135%40darth.lan
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In this PR I propose implementing the zpq_buffered_rx().
zpq_buffered_rx() returns a value greater than zero if there is any data that was fetched by rx_func() but haven't been decompressed yet, in any other case zpq_buffered_rx() returns zero.
Also, I propose renaming the existing zpq_buffered() to zpq_buffered_tx() for clarity.