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1 files changed, 110 insertions, 0 deletions

diff --git a/src/peers.c b/src/peers.c
new file mode 100644
index 0000000..e1825c1
--- /dev/null
+++ b/src/peers.c
@@ -0,0 +1,110 @@
+#include "peers.h"
+
+#include "log.h"
+
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+
+struct peer_entry* peer_table;
+size_t peer_table_size;
+size_t peer_table_load;
+
+int allocate_hashtable() {
+	peer_table_load = 0;
+	peer_table_size = 16;
+	peer_table = calloc(peer_table_size, sizeof(struct peer_entry));
+	if(peer_table == NULL)
+		return PEER_ENOMEM;
+
+	return 0;
+}
+
+static uint64_t hash(struct infohash* key, size_t size) {
+	uint64_t hash = (key->inner[4] << 4) | key->inner[3];
+	return hash % size;
+}
+
+static void find(struct peer_entry* table, size_t size, struct infohash* infohash, struct peer_entry** entry) {
+	uint64_t key = hash(infohash, size);
+	do {
+		*entry = &table[key++];
+		key %= size;
+	} while((*entry)->set && memcmp(&(*entry)->key, infohash, sizeof(struct infohash)) != 0);
+}
+
+static int resize(size_t new_size) {
+	assert((new_size & (new_size - 1)) == 0); // Power of two
+	assert(new_size >= peer_table_load);
+
+	struct peer_entry* new_table = calloc(new_size, sizeof(struct peer_entry));
+	if(peer_table == NULL)
+		return PEER_ENOMEM;
+
+	for(size_t i = 0; i < peer_table_size; i++) {
+		struct peer_entry* entry = &peer_table[i];
+
+		struct peer_entry* new_entry = NULL;
+		find(new_table, new_size, &entry->key, &new_entry);
+
+		assert(!new_entry->set);
+		*new_entry = *entry;
+	}
+
+	free(peer_table);
+
+	peer_table = new_table;
+	peer_table_size = new_size;
+	return 0;
+};
+
+static double load_factor(size_t size, size_t load) {
+	return (double)load / (double)size;
+}
+
+uint64_t next_pow2(uint64_t x) {
+	if(x == 1) return 1;
+	uint16_t leading = __builtin_clzl(x-1);
+	return 1 << (64 - leading);
+}
+
+int add_peer(struct infohash* infohash, struct addr* peer) {
+	assert(peer_table_load < peer_table_size);
+
+	if(load_factor(peer_table_size, peer_table_load + 1) > 0.75) {
+		int rc = resize(peer_table_size * 2);
+		if(rc != 0) return rc;
+	}
+
+	struct peer_entry* entry = NULL;
+	find(peer_table, peer_table_size, infohash, &entry);
+
+	if(!entry->set) {
+		entry->set = true;
+		entry->key = *infohash;
+		peer_table_load++;
+	}
+
+	size_t peern = entry->value_len;
+	if(peern == PEERS_PER_HASH)
+		return PEER_EFULL;
+	assert(peern < PEERS_PER_HASH);
+	entry->value[peern] = *peer;
+	entry->value_len++;
+
+	return 0;
+}
+
+void get_peers(struct infohash* infohash, struct addr *peers[PEERS_PER_HASH], size_t *peers_len) {
+	struct peer_entry* entry;
+	find(peer_table, peer_table_size, infohash, &entry);
+
+	if(!entry->set) {
+		*peers = NULL;
+		*peers_len = 0;
+		return;
+	}
+
+	*peers = entry->value;
+	*peers_len = entry->value_len;
+}