del1.c

bool hash_table_delete(hash_ctx_t* ctx, uint64_t key, hash_old_value_t* old_value) {
	uint32_t bucket_idx = hash_table_bucket_number(ctx, key);
	hash_bucket_t* b = ctx->dir->buckets[bucket_idx];
	uint32_t piece_idx = key % NUMBER_OF_HASH_BUCKET_PIECES;

	ctx->dir->version++;

	if (old_value)
		old_value->exists = false;

	for (size_t i = 0; i < MAX_CHAIN_LENGTH; i++)
	{
		hash_bucket_piece_t* p = &b->pieces[(piece_idx + i) % NUMBER_OF_HASH_BUCKET_PIECES];
		uint8_t* buf = p->data;
		uint8_t* end = p->data + p->bytes_used;
		while (buf < end)
		{
			uint64_t k, v;
			uint8_t* cur_buf_start = buf;
			varint_decode(&buf, &k);
			varint_decode(&buf, &v);

			if (k == key) {

				if (old_value) {
					old_value->exists = true;
					old_value->value = v;
				}

				ptrdiff_t diff = buf - cur_buf_start;
				memmove(cur_buf_start, buf, end - buf);
				p->bytes_used -= (uint8_t)diff;
				b->number_of_entries--;
				ctx->dir->number_of_entries--;
				return true;
			}
		}

		// if we are looking at an overflow page, move to the next one and try to find it there
		if (!p->overflowed)
			break;
	}

	return false;
}