* eth/downloader: refactor downloader + queue
downloader, fetcher: throttle-metrics, fetcher filter improvements, standalone resultcache
downloader: more accurate deliverytime calculation, less mem overhead in state requests
downloader/queue: increase underlying buffer of results, new throttle mechanism
eth/downloader: updates to tests
eth/downloader: fix up some review concerns
eth/downloader/queue: minor fixes
eth/downloader: minor fixes after review call
eth/downloader: testcases for queue.go
eth/downloader: minor change, don't set progress unless progress...
eth/downloader: fix flaw which prevented useless peers from being dropped
eth/downloader: try to fix tests
eth/downloader: verify non-deliveries against advertised remote head
eth/downloader: fix flaw with checking closed-status causing hang
eth/downloader: hashing avoidance
eth/downloader: review concerns + simplify resultcache and queue
eth/downloader: add back some locks, address review concerns
downloader/queue: fix remaining lock flaw
* eth/downloader: nitpick fixes
* eth/downloader: remove the *2*3/4 throttling threshold dance
* eth/downloader: print correct throttle threshold in stats
Co-authored-by: Martin Holst Swende <martin@swende.se>
Co-authored-by: Péter Szilágyi <peterke@gmail.com>
This PR modifies how the metrics library handles `Enabled`: previously,
the package `init` decided whether to serve real metrics or just
dummy-types.
This has several drawbacks:
- During pkg init, we need to determine whether metrics are enabled or
not. So we first hacked in a check if certain geth-specific
commandline-flags were enabled. Then we added a similar check for
geth-env-vars. Then we almost added a very elaborate check for
toml-config-file, plus toml parsing.
- Using "real" types and dummy types interchangeably means that
everything is hidden behind interfaces. This has a performance penalty,
and also it just adds a lot of code.
This PR removes the interface stuff, uses concrete types, and allows for
the setting of Enabled to happen later. It is still assumed that
`metrics.Enable()` is invoked early on.
The somewhat 'heavy' operations, such as ticking meters and exp-decay,
now checks the enable-flag to prevent resource leak.
The change may be large, but it's mostly pretty trivial, and from the
last time I gutted the metrics, I ensured that we have fairly good test
coverage.
---------
Co-authored-by: Felix Lange <fjl@twurst.com>
