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Add get_os_pid/1 function #270

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Mar 14, 2022
Merged

Add get_os_pid/1 function #270

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e723d1a
Add `get_os_pid/1` function
seriyps Mar 3, 2022
37617f3
Rename `get_os_pid` to `get_backend_pid`
seriyps Mar 4, 2022
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8 changes: 8 additions & 0 deletions src/epgsql.erl
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,7 @@
get_parameter/2,
set_notice_receiver/2,
get_cmd_status/1,
get_os_pid/1,
squery/2,
equery/2, equery/3, equery/4,
prepared_query/3,
Expand Down Expand Up @@ -260,6 +261,13 @@ set_notice_receiver(C, PidOrName) ->
get_cmd_status(C) ->
epgsql_sock:get_cmd_status(C).

%% @doc Returns the OS pid of PostgreSQL backend OS process that serves this connection.
%%
%% Similar to `SELECT pg_get_pid()', but does not need network roundtrips.
-spec get_os_pid(connection()) -> integer().
get_os_pid(C) ->
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I find it confusing the terminology around os since this call will be executed from a process within the BEAM that is potentially living in another machine compared to the PG server.
How about renaming it to pg_backend_pid?

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@seriyps seriyps Mar 4, 2022 •
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Good idea. I'd prefer get_backend_pid though, because epgsql is already about postgres. And in Postgres's SQL it's called pg_backend_pid to show that it is not from SQL standard, but Postgres vendor-specific I believe.

epgsql_sock:get_os_pid(C).

-spec squery(connection(), sql_query()) -> epgsql_cmd_squery:response() | epgsql_sock:error().
%% @doc runs simple `SqlQuery' via given `Connection'
%% @see epgsql_cmd_squery
Expand Down
9 changes: 8 additions & 1 deletion src/epgsql_sock.erl
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Expand Up @@ -52,7 +52,8 @@
get_cmd_status/1,
cancel/1,
copy_send_rows/3,
standby_status_update/3]).
standby_status_update/3,
get_os_pid/1]).

-export([handle_call/3, handle_cast/2, handle_info/2, format_status/2]).
-export([init/1, code_change/3, terminate/2]).
Expand Down Expand Up @@ -151,6 +152,9 @@ copy_send_rows(C, Rows, Timeout) ->
standby_status_update(C, FlushedLSN, AppliedLSN) ->
gen_server:call(C, {standby_status_update, FlushedLSN, AppliedLSN}).

-spec get_os_pid(epgsql:connection()) -> integer().
get_os_pid(C) ->
gen_server:call(C, get_os_pid).

%% -- command APIs --

Expand Down Expand Up @@ -230,6 +234,9 @@ handle_call({set_async_receiver, PidOrName}, _From, #state{async = Previous} = S
handle_call(get_cmd_status, _From, #state{complete_status = Status} = State) ->
{reply, {ok, Status}, State};

handle_call(get_os_pid, _From, #state{backend = {Pid, _Key}} = State) ->
{reply, Pid, State};

handle_call({standby_status_update, FlushedLSN, AppliedLSN}, _From,
#state{handler = on_replication,
subproto_state = #repl{last_received_lsn = ReceivedLSN} = Repl} = State) ->
Expand Down
5 changes: 5 additions & 0 deletions src/epgsqla.erl
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Expand Up @@ -15,6 +15,7 @@
get_parameter/2,
set_notice_receiver/2,
get_cmd_status/1,
get_os_pid/1,
squery/2,
equery/2, equery/3,
prepared_query/3,
Expand Down Expand Up @@ -84,6 +85,10 @@ set_notice_receiver(C, PidOrName) ->
get_cmd_status(C) ->
epgsql_sock:get_cmd_status(C).

-spec get_os_pid(epgsql:connection()) -> integer().
get_os_pid(C) ->
epgsql_sock:get_os_pid(C).

-spec squery(epgsql:connection(), epgsql:sql_query()) -> reference().
squery(C, Sql) ->
cast(C, epgsql_cmd_squery, Sql).
Expand Down
5 changes: 5 additions & 0 deletions src/epgsqli.erl
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Expand Up @@ -15,6 +15,7 @@
get_parameter/2,
set_notice_receiver/2,
get_cmd_status/1,
get_os_pid/1,
squery/2,
equery/2, equery/3,
prepared_query/3,
Expand Down Expand Up @@ -81,6 +82,10 @@ set_notice_receiver(C, PidOrName) ->
get_cmd_status(C) ->
epgsql_sock:get_cmd_status(C).

-spec get_os_pid(epgsql:connection()) -> integer().
get_os_pid(C) ->
epgsql_sock:get_os_pid(C).

-spec squery(epgsql:connection(), epgsql:sql_query()) -> reference().
squery(C, Sql) ->
incremental(C, epgsql_cmd_squery, Sql).
Expand Down
11 changes: 10 additions & 1 deletion test/epgsql_SUITE.erl
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Expand Up @@ -139,7 +139,8 @@ groups() ->
listen_notify,
listen_notify_payload,
set_notice_receiver,
get_cmd_status
get_cmd_status,
get_os_pid
],
SubGroups ++
[{epgsql, [], [{group, generic} | Tests]},
Expand Down Expand Up @@ -1419,6 +1420,14 @@ get_cmd_status(Config) ->
?assertEqual({ok, 'commit'}, Module:get_cmd_status(C))
end).

get_os_pid(Config) ->
Module = ?config(module, Config),
epgsql_ct:with_connection(Config, fun(C) ->
{ok, [#column{}], [{PidBin}]} = Module:squery(C, "SELECT pg_backend_pid()"),
Pid = Module:get_os_pid(C),
?assertEqual(PidBin, integer_to_binary(Pid))
end).

range_type(Config) ->
epgsql_ct:with_min_version(Config, [9, 2], fun(_C) ->
check_type(Config, int4range, "int4range(10, 20)", {10, 20}, [
Expand Down
6 changes: 5 additions & 1 deletion test/epgsql_cast.erl
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Expand Up @@ -6,7 +6,8 @@
-module(epgsql_cast).

-export([connect/1, connect/2, connect/3, connect/4, close/1]).
-export([get_parameter/2, set_notice_receiver/2, get_cmd_status/1, squery/2, equery/2, equery/3]).
-export([get_parameter/2, set_notice_receiver/2, get_cmd_status/1, get_os_pid/1,
squery/2, equery/2, equery/3]).
-export([prepared_query/3]).
-export([parse/2, parse/3, parse/4, describe/2, describe/3]).
-export([bind/3, bind/4, execute/2, execute/3, execute/4, execute_batch/2, execute_batch/3]).
Expand Down Expand Up @@ -58,6 +59,9 @@ set_notice_receiver(C, PidOrName) ->
get_cmd_status(C) ->
epgsqla:get_cmd_status(C).

get_os_pid(C) ->
epgsqla:get_os_pid(C).

squery(C, Sql) ->
Ref = epgsqla:squery(C, Sql),
receive_result(C, Ref).
Expand Down
6 changes: 5 additions & 1 deletion test/epgsql_incremental.erl
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Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,8 @@
-module(epgsql_incremental).

-export([connect/1, connect/2, connect/3, connect/4, close/1]).
-export([get_parameter/2, set_notice_receiver/2, get_cmd_status/1, squery/2, equery/2, equery/3]).
-export([get_parameter/2, set_notice_receiver/2, get_cmd_status/1, get_os_pid/1,
squery/2, equery/2, equery/3]).
-export([prepared_query/3]).
-export([parse/2, parse/3, parse/4, describe/2, describe/3]).
-export([bind/3, bind/4, execute/2, execute/3, execute/4, execute_batch/2, execute_batch/3]).
Expand Down Expand Up @@ -56,6 +57,9 @@ set_notice_receiver(C, PidOrName) ->
get_cmd_status(C) ->
epgsqli:get_cmd_status(C).

get_os_pid(C) ->
epgsqli:get_os_pid(C).

squery(C, Sql) ->
Ref = epgsqli:squery(C, Sql),
case receive_results(C, Ref, []) of
Expand Down