## Problem
When Availabilities are created, the amount of bytes in the Availability are reserved in the repo, so those bytes on disk cannot be written to otherwise. When a request for storage is received by a node, if a previously created Availability is matched, an attempt will be made to fill a slot in the request (more accurately, the request's slots are added to the SlotQueue, and eventually those slots will be processed). During download, bytes that were reserved for the Availability were released (as they were written to disk). To prevent more bytes from being released than were reserved in the Availability, the Availability was marked as used during the download, so that no other requests would match the Availability, and therefore no new downloads (and byte releases) would begin. The unfortunate downside to this, is that the number of Availabilities a node has determines the download concurrency capacity. If, for example, a node creates a single Availability that covers all available disk space the operator is willing to use, that single Availability would mean that only one download could occur at a time, meaning the node could potentially miss out on storage opportunities.
## Solution
To alleviate the concurrency issue, each time a slot is processed, a Reservation is created, which takes size (aka reserved bytes) away from the Availability and stores them in the Reservation object. This can be done as many times as needed as long as there are enough bytes remaining in the Availability. Therefore, concurrent downloads are no longer limited by the number of Availabilities. Instead, they would more likely be limited to the SlotQueue's `maxWorkers`.
From a database design perspective, an Availability has zero or more Reservations.
Reservations are persisted in the RepoStore's metadata, along with Availabilities. The metadata store key path for Reservations is ` meta / sales / reservations / <availabilityId> / <reservationId>`, while Availabilities are stored one level up, eg `meta / sales / reservations / <availabilityId> `, allowing all Reservations for an Availability to be queried (this is not currently needed, but may be useful when work to restore Availability size is implemented, more on this later).
### Lifecycle
When a reservation is created, its size is deducted from the Availability, and when a reservation is deleted, any remaining size (bytes not written to disk) is returned to the Availability. If the request finishes, is cancelled (expired), or an error occurs, the Reservation is deleted (and any undownloaded bytes returned to the Availability). In addition, when the Sales module starts, any Reservations that are not actively being used in a filled slot, are deleted.
Having a Reservation persisted until after a storage request is completed, will allow for the originally set Availability size to be reclaimed once a request contract has been completed. This is a feature that is yet to be implemented, however the work in this PR is a step in the direction towards enabling this.
### Unknowns
Reservation size is determined by the `StorageAsk.slotSize`. If during download, more bytes than `slotSize` are attempted to be downloaded than this, then the Reservation update will fail, and the state machine will move to a `SaleErrored` state, deleting the Reservation. This will likely prevent the slot from being filled.
### Notes
Based on #514
* [contracts] Add SlotFreed event
* [integration] allow test node to be stopped twice
* [cli] add --validator option
* [contracts] remove dead code
* [contracts] instantiate OnChainMarket and OnChainClock only once
* [contracts] add Validation
* [sales] remove duplicate import
* [market] add missing import
* [market] subscribe to all SlotFilled events
* [market] add freeSlot()
* [sales] fix warnings
* [market] subscribe to SlotFreed events
* [contracts] fix warning
* [validator] keep track of filled slots
* [validation] remove slots that have ended
* [proving] absorb Proofs into Market
Both Proofs and Market are abstractions around
the Marketplace contract, having them separately
is more trouble than it's worth at the moment.
* [market] add markProofAsMissing()
* [clock] speed up waiting for clock in tests
* [validator] mark proofs as missing
* [timer] fix error on node shutdown
* [cli] handle --persistence and --validator separately
* [market] allow retrieval of proof timeout value
* [validator] do not subscribe to SlotFreed events
Freed slots are already handled in
removeSlotsThatHaveEnded(), and onSlotsFreed()
interfered with its iterator.
* [validator] Start validation at the start of a new period
To decrease the likelihood that we hit the validation timeout.
* [validator] do not mark proofs as missing after timeout
* [market] check whether proof can be marked as missing
* [validator] simplify validation
Simulate a transaction to mark proof as missing, instead
of trying to keep track of all the conditions that may
lead to a proof being marked as missing.
* [build] use nim-ethers PR #40
Uses "pending" blocktag instead of "latest" blocktag
for better simulation of transactions before sending
them.
https://github.com/status-im/nim-ethers/pull/40
* [integration] integration test for validator
* [validator] monitor a maximum number of slots
Adds cli parameter --validator-max-slots.
* [market] fix missing collateral argument
After rebasing, add the new argument to fillSlot calls.
* [build] update to nim-ethers 0.2.5
* [validator] use Set instead of Table to keep track of slots
* [validator] add logging
* [validator] add test for slot failure
* [market] use "pending" blocktag to use more up to date block time
* [contracts] remove unused import
* [validator] fix: wait until after period ends
The smart contract checks that 'end < block.timestamp',
so we need to wait until the block timestamp is greater
than the period end.
* [marketplace] reservations module
- add de/serialization for Availability
- add markUsed/markUnused in persisted availability
- add query for unused
- add reserve/release
- reservation module tests
- split ContractInteractions into client contracts and host contracts
- remove reservations start/stop as the repo start/stop is being managed by the node
- remove dedicated reservations metadata store and use the metadata store from the repo instead
- Split ContractInteractions into:
- ClientInteractions (with purchasing)
- HostInteractions (with sales and proving)
- compilation fix for nim 1.2
[repostore] fix started flag, add tests
[marketplace] persist slot index
For loading the sales state from chain, the slot index was not previously persisted in the contract. Will retrieve the slot index from the contract when the sales state is loaded.
* Revert repostore changes
In favour of separate PR https://github.com/status-im/nim-codex/pull/374.
* remove warnings
* clean up
* tests: stop repostore during teardown
* change constructor type identifier
Change Contracts constructor to accept Contracts type instead of ContractInteractions.
* change constructor return type to Result instead of Option
* fix and split interactions tests
* clean up, fix tests
* find availability by slot id
* remove duplication in host/client interactions
* add test for finding availability by slotId
* log instead of raiseAssert when failed to mark availability as unused
* move to SaleErrored state instead of raiseAssert
* remove unneeded reverse
It appears that order is not preserved in the repostore, so reversing does not have the intended effect here.
* update open api spec for potential rest endpoint errors
* move functions about available bytes to repostore
* WIP: reserve and release availabilities as needed
WIP: not tested yet
Availabilities are marked as used when matched (just before downloading starts) so that future matching logic does not match an availability currently in use.
As the download progresses, batches of blocks are written to disk, and the equivalent bytes are released from the reservation module. The size of the availability is reduced as well.
During a reserve or release operation, availability updates occur after the repo is manipulated. If the availability update operation fails, the reserve or release is rolled back to maintain correct accounting of bytes.
Finally, once download completes, or if an error occurs, the availability is marked as unused so future matching can occur.
* delete availability when all bytes released
* fix tests + cleanup
* remove availability from SalesContext callbacks
Availability is no longer used past the SaleDownloading state in the state machine. Cleanup of Availability (marking unused) is handled directly in the SaleDownloading state, and no longer in SaleErrored or SaleFinished. Likewise, Availabilities shouldn’t need to be handled on node restart.
Additionally, Availability was being passed in SalesContext callbacks, and now that Availability is only used temporarily in the SaleDownloading state, Availability is contextually irrelevant to the callbacks, except in OnStore possibly, though it was not being consumed.
* test clean up
* - remove availability from callbacks and constructors from previous commit that needed to be removed (oopsie)
- fix integration test that checks availabilities
- there was a bug fixed that crashed the node due to a missing `return success` in onStore
- the test was fixed by ensuring that availabilities are remaining on the node, and the size has been reduced
- change Availability back to non-ref object and constructor back to init
- add trace logging of all state transitions in state machine
- add generally useful trace logging
* fixes after rebase
1. Fix onProve callbacks
2. Use Slot type instead of tuple for retrieving active slot.
3. Bump codex-contracts-eth that exposes getActivceSlot call.
* swap contracts branch to not support slot collateral
Slot collateral changes in the contracts require further changes in the client code, so we’ll skip those changes for now and add in a separate commit.
* modify Interactions and Deployment constructors
- `HostInteractions` and `ClientInteractions` constructors were simplified to take a contract address and no overloads
- `Interactions` prepared simplified so there are no overloads
- `Deployment` constructor updated so that it takes an optional string parameter, instead `Option[string]`
* Move `batchProc` declaration
`batchProc` needs to be consumed by both `node` and `salescontext`, and they can’t reference each other as it creates a circular dependency.
* [reservations] rename `available` to `hasAvailable`
* [reservations] default error message to inner error msg
* add SaleIngored state
When a storage request is handled but the request does match availabilities, the sales agent machine is sent to the SaleIgnored state. In addition, the agent is constructed in a way that if the request is ignored, the sales agent is removed from the list of active agents being tracked in the sales module.
markspanbroek
Adam Uhlíř
Ben Bierens
Eric
Dmitriy Ryajov
Eric Mastro