Implement ringWrite

1 files changed, 40 insertions, 0 deletions

diff --git a/ring.c b/ring.c
new file mode 100644
index 0000000..40fb7df
--- /dev/null
+++ b/ring.c
@@ -0,0 +1,40 @@
+/* Copyright (C) 2019  C. McEnroe <june@causal.agency>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <assert.h>
+#include <err.h>
+#include <stdlib.h>
+#include <sysexits.h>
+#include <time.h>
+
+#include "bounce.h"
+
+enum { RingLen = 4096 };
+static_assert(!(RingLen & (RingLen - 1)), "power of two RingLen");
+
+static struct {
+	char *lines[RingLen];
+	time_t times[RingLen];
+	size_t write;
+} ring;
+
+void ringWrite(const char *line) {
+	size_t i = ring.write++ % RingLen;
+	if (ring.lines[i]) free(ring.lines[i]);
+	ring.times[i] = time(NULL);
+	ring.lines[i] = strdup(line);
+	if (!ring.lines[i]) err(EX_OSERR, "strdup");
+}