Module Evm_node_lib_dev.Kernel_download

download ~preimages_endpoint ~preimages ~root_hash ?num_download_retries ?concurrency ?progress () fetches from preimages_endpoint all the preimages the kernel root_hash is made of, and stores them in the preimages directory. A preimage whose hash does not match the one it was requested for is downloaded again at most num_download_retries times (once by default).

concurrency is how many preimages are fetched at a time (one by default, that is, sequentially), and also the number of connections opened onto preimages_endpoint. It must be at least one; the function fails otherwise. Only the content pages of the kernel are fetched concurrently; the hash pages naming them are walked one level at a time, as a level cannot be known before the level above it has been read.

A preimage already present in preimages is read from there instead of being fetched again, so an interrupted download resumes where it stopped.

When progress is set (it is not by default), a progress bar reporting the number of preimages downloaded out of the total is displayed on the terminal.