xap_helper.h: memoize Xapian handles with khashl

Since we're already using khashl in the C++ implementation,
get rid of tsearch(3) and friends as well.  Relying on hash
tables in both the Perl and C(++) implementation reduces
cognitive load for hackers.

diff --git a/lib/PublicInbox/xap_helper.h b/lib/PublicInbox/xap_helper.h
index 05b3b8c91c0d55dad179e80b99547855d9c6cff7..44e0d63e01d727c0ca8c831d675a54a9ed826ce9 100644 (file)
--- a/lib/PublicInbox/xap_helper.h
+++ b/lib/PublicInbox/xap_helper.h
@@ -37,7 +37,6 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <limits.h>
-#include <search.h>
 #include <signal.h>
 #include <stddef.h>
 #include <stdint.h>
@@ -116,6 +115,31 @@ static void *xreallocarray(void *ptr, size_t nmemb, size_t size)
        return ret;
 }
 
+#include "khashl.h"
+
+struct srch {
+       int ckey_len; // int for comparisons
+       unsigned qp_flags;
+       bool qp_extra_done;
+       Xapian::Database *db;
+       Xapian::QueryParser *qp;
+       unsigned char ckey[]; // $shard_path0\0$shard_path1\0...
+};
+
+static khint_t srch_hash(const struct srch *srch)
+{
+       return kh_hash_bytes(srch->ckey_len, srch->ckey);
+}
+
+static int srch_eq(const struct srch *a, const struct srch *b)
+{
+       return a->ckey_len == b->ckey_len ?
+               !memcmp(a->ckey, b->ckey, (size_t)a->ckey_len) : 0;
+}
+
+KHASHL_CSET_INIT(KH_LOCAL, srch_set, srch_set, struct srch *,
+               srch_hash, srch_eq)
+static srch_set *srch_cache;
 // sock_fd is modified in signal handler, yes, it's SOCK_SEQPACKET
 static volatile int sock_fd = STDIN_FILENO;
 static sigset_t fullset, workerset;
@@ -124,7 +148,6 @@ static bool alive = true;
 static FILE *orig_err = stderr;
 #endif
 static int orig_err_fd = -1;
-static void *srch_tree; // tsearch + tdelete + twalk
 static pid_t *worker_pids; // nr => pid
 #define WORKER_MAX USHRT_MAX
 static unsigned long nworker, nworker_hwm;
@@ -144,15 +167,6 @@ enum exc_iter {
        ITER_ABORT
 };
 
-struct srch {
-       int ckey_len; // int for comparisons
-       unsigned qp_flags;
-       bool qp_extra_done;
-       Xapian::Database *db;
-       Xapian::QueryParser *qp;
-       char ckey[]; // $shard_path0\0$shard_path1\0...
-};
-
 #define MY_ARG_MAX 256
 typedef bool (*cmd)(struct req *);
 
@@ -435,7 +449,6 @@ static bool cmd_test_sleep(struct req *req)
        for (;;) poll(NULL, 0, 10);
        return false;
 }
-#include "khashl.h"
 #include "xh_mset.h" // read-only (WWW, IMAP, lei) stuff
 #include "xh_cidx.h" // CodeSearchIdx.pm stuff
 
@@ -526,15 +539,6 @@ again:
        return false;
 }
 
-static int srch_cmp(const void *pa, const void *pb) // for tfind|tsearch
-{
-       const struct srch *a = (const struct srch *)pa;
-       const struct srch *b = (const struct srch *)pb;
-       int diff = a->ckey_len - b->ckey_len;
-
-       return diff ? diff : memcmp(a->ckey, b->ckey, (size_t)a->ckey_len);
-}
-
 static bool is_chert(const char *dir)
 {
        char iamchert[PATH_MAX];
@@ -625,9 +629,8 @@ static void srch_init_extra(struct req *req)
        req->srch->qp_extra_done = true;
 }
 
-static void free_srch(void *p) // tdestroy
+static void srch_free(struct srch *srch)
 {
-       struct srch *srch = (struct srch *)p;
        delete srch->qp;
        delete srch->db;
        free(srch);
@@ -643,7 +646,6 @@ static void dispatch(struct req *req)
        } kbuf;
        char *end;
        FILE *kfp;
-       struct srch **s;
        req->threadid = ULLONG_MAX;
        for (c = 0; c < (int)MY_ARRAY_SIZE(cmds); c++) {
                if (cmds[c].fn_len == size &&
@@ -725,18 +727,19 @@ static void dispatch(struct req *req)
        kbuf.srch->ckey_len = size - offsetof(struct srch, ckey);
        if (kbuf.srch->ckey_len <= 0 || !req->dirc)
                ABORT("no -d args (or too many)");
-       s = (struct srch **)tsearch(kbuf.srch, &srch_tree, srch_cmp);
-       if (!s) err(EXIT_FAILURE, "tsearch"); // likely ENOMEM
-       req->srch = *s;
-       if (req->srch != kbuf.srch) { // reuse existing
-               free_srch(kbuf.srch);
+
+       int absent;
+       khint_t ki = srch_set_put(srch_cache, kbuf.srch, &absent);
+       assert(ki < kh_end(srch_cache));
+       req->srch = kh_key(srch_cache, ki);
+       if (!absent) { // reuse existing
+               assert(req->srch != kbuf.srch);
+               srch_free(kbuf.srch);
                req->srch->db->reopen();
        } else if (!srch_init(req)) {
-               assert(kbuf.srch == *((struct srch **)tfind(
-                                       kbuf.srch, &srch_tree, srch_cmp)));
-               void *del = tdelete(kbuf.srch, &srch_tree, srch_cmp);
-               assert(del);
-               free_srch(kbuf.srch);
+               int gone = srch_set_del(srch_cache, ki);
+               assert(gone);
+               srch_free(kbuf.srch);
                goto cmd_err; // srch_init already warned
        }
        if (req->qpfxc && !req->srch->qp_extra_done)
@@ -895,10 +898,16 @@ static void start_workers(void)
 static void cleanup_all(void)
 {
        cleanup_pids();
-#ifdef __GLIBC__
-       tdestroy(srch_tree, free_srch);
-       srch_tree = NULL;
-#endif
+       if (!srch_cache)
+               return;
+
+       khint_t k;
+       for (k = kh_begin(srch_cache); k != kh_end(srch_cache); k++) {
+               if (kh_exist(srch_cache, k))
+                       srch_free(kh_key(srch_cache, k));
+       }
+       srch_set_destroy(srch_cache);
+       srch_cache = NULL;
 }
 
 static void parent_reopen_logs(void)
@@ -1040,6 +1049,7 @@ int main(int argc, char *argv[])
 
        mail_nrp_init();
        code_nrp_init();
+       srch_cache = srch_set_init();
        atexit(cleanup_all);
 
        if (!STDERR_ASSIGNABLE) {