Add rpmlogOnce() and rpmlogReset()

These are internal only for now to allow us gain soem more confidence on
the design.

rpmlogOnce allows showing a log message only once. rpmlogReset allows purging
the list of known message keys for a given domain. This allows for different
live times e.g. per transaction or per package.

Resolves: #3395

rpmio/rpmlog.cc

@@ -7,6 +7,7 @@
 #include <mutex>
 #include <shared_mutex>
 #include <vector>
+#include <map>
 #include <string>
 
 #include <stdarg.h>
@@ -22,6 +23,7 @@ struct rpmlogCtx_s {
     unsigned mask;
     int nrecsPri[RPMLOG_NPRIS];
     std::vector<rpmlogRec_s> recs;
+    std::map<uint64_t, std::map<std::pair<int, std::string>, int>> seen;
     rpmlogCallback cbfunc;
     rpmlogCallbackData cbdata;
     FILE *stdlog;
@@ -41,7 +43,7 @@ using rdlock = std::shared_lock<std::shared_mutex>;
 static rpmlogCtx rpmlogCtxAcquire()
 {
     static struct rpmlogCtx_s _globalCtx = { RPMLOG_UPTO(RPMLOG_NOTICE),
-					     {0}, {}, NULL, NULL, NULL };
+					     {0}, {}, {}, NULL, NULL, NULL };
     return &_globalCtx;
 }
 
@@ -127,6 +129,7 @@ void rpmlogClose (void)
     wrlock lock(ctx->mutex);
 
     ctx->recs.clear();
+    ctx->seen.clear();
     memset(ctx->nrecsPri, 0, sizeof(ctx->nrecsPri));
 }
 
@@ -412,3 +415,36 @@ void rpmlog (int code, const char *fmt, ...)
 exit:
     errno = saved_errno;
 }
+
+int rpmlogOnce (uint64_t domain, const char * key, int code, const char *fmt, ...)
+{
+    int saved_errno = errno;
+    rpmlogCtx ctx = rpmlogCtxAcquire();
+    int newkey = 0;
+
+    if (ctx) {
+	wrlock lock(ctx->mutex);
+	/* members get initialized automatically on first access */
+	newkey = !(ctx->seen[domain][{code, key}]++);
+    }
+
+    if (newkey) {
+	va_list ap;
+	char *msg = NULL;
+	va_start(ap, fmt);
+	if (rvasprintf(&msg, fmt, ap) >= 0) {
+	    rpmlog(code, msg);
+	    free(msg);
+	}
+	va_end(ap);
+    }
+    errno = saved_errno;
+    return newkey;
+}
+
+void rpmlogReset(uint64_t domain, int mode=0)
+{
+    rpmlogCtx ctx = rpmlogCtxAcquire();
+    wrlock lock(ctx->mutex);
+    ctx->seen.erase(domain);
+}

rpmio/rpmlog_internal.hh

@@ -0,0 +1,23 @@
+#ifndef H_RPMLOG_INTERNAL
+#define H_RPMLOG_INTERNAL 1
+
+
+/** \ingroup rpmlog
+ * Generate a log message using FMT string and option arguments.
+ * Only actually log on the first time passing the key value
+ * @param domain	group of messages to be reset together
+ * @param key		key to match log messages together
+ * @param code		rpmlogLvl
+ * @param fmt		format string and parameter to render
+ * @return		1 if actually logging 0 otherwise
+ */
+int rpmlogOnce (uint64_t domain, const char * key, int code, const char *fmt, ...) RPM_GNUC_PRINTF(4, 5);
+
+/** \ingroup rpmlog
+ * Clear memory of logmessages for a given domain
+ * @param domain	group of messages to be reset together
+ * @param mode		curretnly only 0 supported whihc drops everything
+ */
+void rpmlogReset(uint64_t domain, int mode=0);
+
+#endif