// generate creates the actual DAG. it can be called from multiple
// goroutines. the first call will generate the DAG, subsequent
// calls wait until it is generated.
func (d *dag) generate() {
d.gen.Do(func() {
var (
started = time.Now()
seedHash = makeSeedHash(d.epoch)
blockNum = C.uint64_t(d.epoch * epochLength)
cacheSize = C.ethash_get_cachesize(blockNum)
dagSize = C.ethash_get_datasize(blockNum)
)
if d.test {
cacheSize = cacheSizeForTesting
dagSize = dagSizeForTesting
}
if d.dir == "" {
d.dir = DefaultDir
}
glog.V(logger.Info).Infof("Generating DAG for epoch %d (%x)", d.epoch, seedHash)
// Generate a temporary cache.
// TODO: this could share the cache with Light
cache := C.ethash_light_new_internal(cacheSize, (*C.ethash_h256_t)(unsafe.Pointer(&seedHash[0])))
defer C.ethash_light_delete(cache)
// Generate the actual DAG.
d.ptr = C.ethash_full_new_internal(
C.CString(d.dir),
hashToH256(seedHash),
dagSize,
cache,
(C.ethash_callback_t)(unsafe.Pointer(C.ethashGoCallback_cgo)),
)
if d.ptr == nil {
panic("ethash_full_new IO or memory error")
}
runtime.SetFinalizer(d, freeDAG)
glog.V(logger.Info).Infof("Done generating DAG for epoch %d, it took %v", d.epoch, time.Since(started))
})
}
func freeCache(cache *cache) {
C.ethash_light_delete(cache.ptr)
cache.ptr = nil
}