From b2421760716af830f2937c3b8b759d652ce75c9b Mon Sep 17 00:00:00 2001
From: Yorhel <git@yorhel.nl>
Date: Sun, 2 Feb 2025 14:36:54 +0100
Subject: [PATCH] pg: Adventures in writing a new postgresql client

---
 FU.xs             | 54 +++++++++++++++++++++++++++++++++++++++++++++--
 FU/Benchmarks.pod |  5 ++++-
 FU/PG.pm          | 11 ++++++++++
 Makefile.PL       |  1 +
 README.md         |  1 -
 c/pgconn.c        | 47 +++++++++++++++++++++++++++++++++++++++++
 t/pgconnect.t     | 17 +++++++++++++++
 7 files changed, 132 insertions(+), 4 deletions(-)
 create mode 100644 FU/PG.pm
 create mode 100644 c/pgconn.c
 create mode 100644 t/pgconnect.t

diff --git a/FU.xs b/FU.xs
index 7b7bb48..ee9dd19 100644
--- a/FU.xs
+++ b/FU.xs
@@ -1,3 +1,5 @@
+#include <dlfcn.h>
+
 #define PERL_NO_GET_CONTEXT
 #include "EXTERN.h"
 #include "perl.h"
@@ -6,12 +8,28 @@
 #include "c/common.c"
 #include "c/jsonfmt.c"
 #include "c/jsonparse.c"
+#include "c/pgconn.c"
+
+
+MODULE = FU
+
+PROTOTYPES: DISABLE
+
+
+TYPEMAP: <<EOT
+TYPEMAP
+fupg_conn *   FUPG_CONN
+
+INPUT
+FUPG_CONN
+    if (sv_derived_from($arg, \"FU::PG::conn\")) $var = (fupg_conn *)SvIVX(SvRV($arg));
+    else croak(\"invalid object\");
+#"
+EOT
 
 
 MODULE = FU   PACKAGE = FU::Util
 
-PROTOTYPES: DISABLE
-
 void json_format(SV *val, ...)
   CODE:
     ST(0) = fujson_fmt_xs(aTHX_ ax, items, val);
@@ -19,3 +37,35 @@ void json_format(SV *val, ...)
 void json_parse(SV *val, ...)
   CODE:
     ST(0) = fujson_parse_xs(aTHX_ ax, items, val);
+
+
+
+MODULE = FU   PACKAGE = FU::PG
+
+void _load_libpq()
+  CODE:
+    if (!PQconnectdb) fupg_load();
+
+int lib_version()
+  CODE:
+    RETVAL = PQlibVersion();
+  OUTPUT:
+    RETVAL
+
+void connect(const char *pkg, const char *conninfo)
+  CODE:
+    (void)pkg;
+    ST(0) = sv_setref_pv(sv_newmortal(), "FU::PG::conn", fupg_connect(aTHX_ conninfo));
+
+
+MODULE = FU   PACKAGE = FU::PG::conn
+
+int server_version(fupg_conn *c)
+  CODE:
+    RETVAL = PQserverVersion(c->conn);
+  OUTPUT:
+    RETVAL
+
+void DESTROY(fupg_conn *c)
+  CODE:
+    fupg_destroy(c);
diff --git a/FU/Benchmarks.pod b/FU/Benchmarks.pod
index 55f00db..651160f 100644
--- a/FU/Benchmarks.pod
+++ b/FU/Benchmarks.pod
@@ -17,6 +17,9 @@ be a good measure". I've used these benchmarks to find and optimize hotspots in
 FU, which in turn means these numbers may look better than they are in
 real-world use.
 
+B<DISCLAIMER#3:> Many of these benchmarks exists solely to test edge case
+performance, these numbers are not representative for real-world use.
+
 =head1 MODULE VERSIONS
 
 The following module versions were used:
@@ -39,7 +42,7 @@ The following module versions were used:
 
 =head1 BENCHMARKS
 
-=head2 JSON Formatting
+=head2 JSON Parsing & Formatting
 
 These benchmarks run on large-ish arrays with repeated values. JSON encoding is
 sufficiently fast that Perl function calling overhead tends to dominate for
diff --git a/FU/PG.pm b/FU/PG.pm
new file mode 100644
index 0000000..7b8f10b
--- /dev/null
+++ b/FU/PG.pm
@@ -0,0 +1,11 @@
+package FU::PG 0.1;
+use v5.36;
+use FU::XS;
+
+_load_libpq();
+
+package FU::PG::conn {
+    sub lib_version { FU::PG::lib_version() }
+};
+
+1;
diff --git a/Makefile.PL b/Makefile.PL
index 29553b7..86cce2c 100644
--- a/Makefile.PL
+++ b/Makefile.PL
@@ -1,6 +1,7 @@
 use ExtUtils::MakeMaker;
 use Config;
 
+os_unsupported if $^O eq 'MSWin32'; # I don't know on which OS'es the code will work exactly, but this one I can easily rule out.
 os_unsupported if $Config{ivsize} < 8;
 os_unsupported if $Config{usequadmath};
 
diff --git a/README.md b/README.md
index fbf4148..a3a7705 100644
--- a/README.md
+++ b/README.md
@@ -20,7 +20,6 @@ Things that may or may not happen:
 - FU::HTTPServer / FU::FastCGI - Minimal libs to support the web framework.
 - FU::JSON - JSON::{XS,PP,etc}-compatible wrapper around FU::Util's JSON functions? I prolly won't need this myself, but could be handy.
 - FU::Log - Basic logger.
-- FU::PG - PostgreSQL client with support for custom types and a small query builder.
 - FU::Util additions: `uri_escape`, `VNDB::Util::query_encode`, `scrypt`, `urandom`.
 - FU::Validate - TUWF::Validate & normalization with some improvements.
 - FU::XML - TUWF::XMLXS with some improvements.
diff --git a/c/pgconn.c b/c/pgconn.c
new file mode 100644
index 0000000..256ff56
--- /dev/null
+++ b/c/pgconn.c
@@ -0,0 +1,47 @@
+typedef struct PGconn PGconn;
+
+#define PG_FUNCS \
+    X(PQconnectdb, PGconn *, const char *) \
+    X(PQerrorMessage, char *, const PGconn *) \
+    X(PQfinish, void, PGconn *) \
+    X(PQlibVersion, int, void) \
+    X(PQserverVersion, int, const PGconn *) \
+    X(PQstatus, int, const PGconn *)
+
+#define X(n, r, ...) static r (*n)(__VA_ARGS__);
+PG_FUNCS
+#undef X
+
+static void fupg_load() {
+    void *handle = dlopen("libpq.so", RTLD_LAZY);
+    if (!handle) croak("Unable to load libpq: %s", dlerror());
+#define X(n, ...) if (!(n = dlsym(handle, #n))) croak("Unable to load libpq: %s", dlerror());
+PG_FUNCS
+#undef X
+}
+
+#undef PG_FUNCS
+
+
+typedef struct {
+    PGconn *conn;
+} fupg_conn;
+
+fupg_conn *fupg_connect(pTHX_ const char *str) {
+    SV *sv;
+    PGconn *conn = PQconnectdb(str);
+    if (PQstatus(conn) != 0) {
+        sv = newSVpvf("FU::PG connection error: %s", PQerrorMessage(conn));
+        PQfinish(conn);
+        croak_sv(sv);
+    }
+
+    fupg_conn *c = safecalloc(1, sizeof(fupg_conn));
+    c->conn = conn;
+    return c;
+}
+
+static void fupg_destroy(fupg_conn *c) {
+    PQfinish(c->conn);
+    safefree(c);
+}
diff --git a/t/pgconnect.t b/t/pgconnect.t
new file mode 100644
index 0000000..da10a36
--- /dev/null
+++ b/t/pgconnect.t
@@ -0,0 +1,17 @@
+use v5.36;
+use Test::More;
+
+plan skip_all => $@ if !eval { require FU::PG; } && $@ =~ /Unable to load libpq/;
+plan skip_all => 'Please set FU_TEST_DB to a PostgreSQL connection string to run these tests' if !$ENV{FU_TEST_DB};
+
+ok !eval { FU::PG->connect("invalid") };
+
+ok FU::PG::lib_version() > 100000;
+
+my $conn = FU::PG->connect($ENV{FU_TEST_DB});
+
+is ref $conn, 'FU::PG::conn';
+ok $conn->server_version() > 100000;
+is $conn->lib_version(), FU::PG::lib_version();
+
+done_testing;