1 files changed, 150 insertions, 0 deletions
diff --git a/lib/extfile.c b/lib/extfile.c
new file mode 100644
index 0000000..fdd94eb
--- /dev/null
+++ b/lib/extfile.c
@@ -0,0 +1,150 @@
+// SPDX-License-Identifier: LGPL-3.0-or-later
+
+#include "impl.h"
+
+#define MAX_GEN ((uint32_t)2147483648u)
+
+static bool hkvs_extfile_gc(hkvs *c) {
+	hkvs_extfile *ext = c->extfiles;
+	size_t n = c->n_extfiles;
+
+	uint32_t gen = c->extfile_gen;
+	uint32_t max = 0;
+	for(size_t i = 0; i < n; i++) {
+		uint32_t diff = gen - ext[i].gen;
+		if(diff > max) max = diff;
+	}
+	if(max == 0) return false;
+
+	if(max >= MAX_GEN) max = MAX_GEN;
+
+	hkvs_io *io = c->io;
+	size_t i = 0;
+	for(size_t j = 0; j < n; j++) {
+		uint32_t diff = gen - ext[j].gen;
+		if(diff >= max) {
+			io->close(io, ext[j].fi, ext[j].addr, ext[j].size);
+		} else {
+			ext[i++] = ext[j];
+		}
+	}
+
+	if(n > 64 && i < n / 2) {
+		ext = realloc(ext, i * sizeof(hkvs_extfile));
+		if(ext) {
+			c->extfiles = ext;
+			c->alloc_extfiles = i;
+		}
+	}
+
+	c->n_extfiles = i;
+	return true;
+}
+
+static int hkvs_extfile_reserve_slow(hkvs *c) {
+	if(c->n_extfiles > 16) {
+		if(hkvs_extfile_gc(c)) return 0;
+	}
+
+	size_t n = c->n_extfiles;
+	hkvs_extfile *ext = c->extfiles;
+	n += (n >> 2) + 1;
+	ext = realloc(ext, n * sizeof(hkvs_extfile));
+	if(!ext) return -ENOMEM;
+	c->extfiles = ext;
+	c->alloc_extfiles = n;
+	return 0;
+}
+
+HKVS_INLINE int hkvs_extfile_reserve(hkvs *c) {
+	if(c->n_extfiles != c->alloc_extfiles) return 0;
+	return hkvs_extfile_reserve_slow(c);
+}
+
+int hkvs_extfile_create(hkvs *c, uint64_t *pfi, char **paddr, size_t size, bool pin) {
+	int r = hkvs_extfile_reserve(c);
+	if(r < 0) return r;
+
+	uint64_t fi;
+	char *addr;
+	r = c->io->create(c->io, &fi, &addr, size);
+	if(r < 0) return r;
+	if(fi == 0) hkvs_die("created file 0");
+
+	c->extfiles[c->n_extfiles++] = (hkvs_extfile) {
+		.fi = fi,
+		.addr = addr,
+		.size = size,
+		.gen = pin ? c->extfile_gen : c->extfile_gen - 1,
+	};
+
+	*pfi = fi;
+	*paddr = addr;
+
+	return 0;
+}
+
+HKVS_MUSTCHECK bool hkvs_extfile_find(hkvs *c, uint64_t fi, size_t *pslot) {
+	hkvs_extfile *ext = c->extfiles;
+	size_t n = c->n_extfiles;
+	for(size_t i = 0; i < n; i++) {
+		if(ext[i].fi == fi) {
+			*pslot = i;
+			return true;
+		}
+	}
+	return false;
+}
+
+HKVS_MUSTCHECK int hkvs_extfile_open(hkvs *c, uint64_t fi, size_t *pslot, size_t want_size) {
+	if(fi == 0) return -EBADMSG;
+
+	hkvs_extfile *ext = c->extfiles;
+	size_t n = c->n_extfiles;
+	for(size_t i = 0; i < n; i++) {
+		if(ext[i].fi == fi) {
+			if(ext[i].size < want_size) return -EBADMSG;
+			*pslot = i;
+			return 0;
+		}
+	}
+
+	int r = hkvs_extfile_reserve(c);
+	if(r < 0) return 0;
+
+	char *addr;
+	size_t size;
+	r = c->io->open(c->io, fi, &addr, &size);
+	if(r < 0) return r;
+
+	size_t slot = c->n_extfiles++;
+	c->extfiles[slot] = (hkvs_extfile) {
+		.fi = fi,
+		.addr = addr,
+		.size = size,
+		.gen = c->extfile_gen - 1,
+	};
+
+	if(size < want_size) return -EBADMSG;
+
+	*pslot = slot;
+	return 0;
+}
+
+void hkvs_extfile_close(hkvs *c, size_t slot) {
+	hkvs_extfile *ext = c->extfiles;
+	size_t n = c->n_extfiles;
+	hkvs_assume(slot < n);
+	n--;
+	c->n_extfiles = n;
+
+	c->io->close(c->io, ext[slot].fi, ext[slot].addr, ext[slot].size);
+	if(slot != n) ext[slot] = ext[n];
+}
+
+void hkvs_put_records(hkvs *c) {
+	c->extfile_gen++;
+	if(c->extfile_gen % MAX_GEN == 0) {
+		hkvs_extfile_gc(c);
+	}
+}