pg: Statement preparing + inspection; less wonky object handling?

c/pgconn.c

@@ -1,5 +1,7 @@
 typedef struct {
+    SV *self;
     PGconn *conn;
+    UV prep_counter;
 } fupg_conn;
 
 
@@ -61,7 +63,7 @@ static void fupg_result_croak(PGresult *r, const char *action, const char *query
     croak_sv(sv_bless(sv_2mortal(newRV_noinc((SV *)hv)), gv_stashpvs("FU::PG::error", GV_ADD)));
 }
 
-static fupg_conn *fupg_connect(pTHX_ const char *str) {
+static SV *fupg_connect(pTHX_ const char *str) {
     PGconn *conn = PQconnectdb(str);
     if (PQstatus(conn) != 0) {
         SV *sv = fupg_conn_errsv(conn, "connect");
@@ -71,7 +73,7 @@ static fupg_conn *fupg_connect(pTHX_ const char *str) {
 
     fupg_conn *c = safecalloc(1, sizeof(fupg_conn));
     c->conn = conn;
-    return c;
+    return fupg_selfobj(c, "FU::PG::conn");
 }
 
 static void fupg_destroy(fupg_conn *c) {
@@ -79,7 +81,7 @@ static void fupg_destroy(fupg_conn *c) {
     safefree(c);
 }
 
-static SV *fupg_exec(fupg_conn *c, const char *sql) {
+static SV *fupg_exec(pTHX_ fupg_conn *c, const char *sql) {
     PGresult *r = PQexec(c->conn, sql);
     if (!r) fupg_conn_croak(c, "exec");
     switch (PQresultStatus(r)) {
@@ -98,3 +100,99 @@ static SV *fupg_exec(fupg_conn *c, const char *sql) {
     PQclear(r);
     return ret;
 }
+
+typedef struct {
+    /* Set in $conn->q() */
+    SV *self;
+    fupg_conn *conn; /* has a refcnt on conn->self */
+    char *query;
+    SV **bind;
+    int bindn;
+    /* Set during prepare */
+    char name[32];
+    int prepared;
+    PGresult *describe;
+} fupg_st;
+
+static SV *fupg_q(pTHX_ fupg_conn *c, const char *query, I32 ax, I32 argc) {
+    fupg_st *st = safecalloc(1, sizeof(fupg_st));
+    st->conn = c;
+    SvREFCNT_inc(c->self);
+
+    st->query = savepv(query);
+    if (argc > 2) {
+        st->bind = safemalloc((argc-2) * sizeof(SV *));
+        I32 i = 2;
+        while (i < argc) {
+            st->bind[st->bindn] = newSV(0);
+            sv_setsv(st->bind[st->bindn], ST(i));
+            st->bindn++;
+        }
+    }
+
+    return fupg_selfobj(st, "FU::PG::st");
+}
+
+static void fupg_st_prepare(pTHX_ fupg_st *st) {
+    if (st->describe) return;
+    if (st->prepared) croak("invalid attempt to re-prepare invalid statement");
+
+    /* TODO: This is where we check for any cached prepared statements */
+
+    snprintf(st->name, sizeof(st->name), "fupg%"UVuf, ++st->conn->prep_counter);
+
+    /* TODO: Pipeline these two commands, no need for two round-trips with the server */
+    PGresult *r = PQprepare(st->conn->conn, st->name, st->query, 0, NULL);
+    if (!r) fupg_conn_croak(st->conn , "prepare");
+    if (PQresultStatus(r) != PGRES_COMMAND_OK)
+        fupg_result_croak(r, "prepare", st->query);
+    PQclear(r);
+    st->prepared = 1;
+
+    r = PQdescribePrepared(st->conn->conn, st->name);
+    if (!r) fupg_conn_croak(st->conn , "prepare");
+    if (PQresultStatus(r) != PGRES_COMMAND_OK)
+        fupg_result_croak(r, "prepare", st->query);
+    st->describe = r;
+}
+
+static SV *fupg_st_params(pTHX_ fupg_st *st) {
+    fupg_st_prepare(st);
+    int i, nparams = PQnparams(st->describe);
+    AV *av = newAV_alloc_x(nparams);
+    for (i=0; i<nparams; i++) {
+        HV *hv = newHV();
+        hv_stores(hv, "oid", newSViv(PQparamtype(st->describe, i)));
+        av_push_simple(av, newRV_noinc((SV *)hv));
+    }
+    return sv_2mortal(newRV_noinc((SV *)av));
+}
+
+static SV *fupg_st_columns(pTHX_ fupg_st *st) {
+    fupg_st_prepare(st);
+    int i, ncols = PQnfields(st->describe);
+    AV *av = newAV_alloc_x(ncols);
+    for (i=0; i<ncols; i++) {
+        HV *hv = newHV();
+        const char *name = PQfname(st->describe, i);
+        hv_stores(hv, "name", newSVpvn_utf8(name, strlen(name), 1));
+        hv_stores(hv, "oid", newSViv(PQftype(st->describe, i)));
+        int tmod = PQfmod(st->describe, i);
+        if (tmod >= 0) hv_stores(hv, "typemod", newSViv(tmod));
+        av_push_simple(av, newRV_noinc((SV *)hv));
+    }
+    return sv_2mortal(newRV_noinc((SV *)av));
+}
+
+static void fupg_st_destroy(fupg_st *st) {
+    int i;
+    /* Ignore failure, this is just a best-effort attempt to free up resources on the backend */
+    if (st->prepared) PQclear(PQclosePrepared(st->conn->conn, st->name));
+
+    if (st->query) safefree(st->query);
+    for (i=0; i < st->bindn; i++) SvREFCNT_dec(st->bind[i]);
+    if (st->bind) safefree(st->bind);
+    if (st->describe) PQclear(st->describe);
+    SvREFCNT_dec(st->conn->self);
+    safefree(st);
+}