###### tags: `strunfun`

# abicachemodule

## Description
Convenience Module to cache Contract ABIs in Local Storage. This serves the purpose that we could load most any ABI on-the-fly and have recently used available without loading.
So the main usecase is calling the`getABI` function. Where we provide the `address"` of the contract. Which should at best be a verified contract on etherscan from the mainnet.
It would return `undefined` if we neither have the contract cached nor it is retrievable over the ABI Cache Service.

## Expectation to the Environment
- `allModules.networkmodule` - dependency [networkmodule](https://hackmd.io/mJLlooBoT-u0AxreoISIkQ?view)
- service access [ABI Cache Service](https://hackmd.io/taH_79GQSSiMeZaTlhGkLQ?view)
- `allModules.statemodule` - dependency [statemodule](https://hackmd.io/nn708ujuRLeo0crmfr2X_Q?view)
- `allModules.configmodule` - dependency configmodule
- `allModules.configmodule.ABICacheSize` - config `ABICacheSize`

## Structure
- `network°`
- `state°`
- `addressABIMap°`
- `cacheEntries[`
- `maxCacheSize#`
- `.initialize§`
- `touchCache§` `address"`
- `.getABI§` `address"`

## Specification
- `network°` = the reference to the external `networkmodule`
- `state°` = the reference to the external `statemodule`
- `addressABIMap°` = map which maps contract `address"` to the corresponding `abi°` - is reflected as `persistentState`
- `cacheEntries[` =
- list keeping track of the currently cached contracts by their `address"`
- is in order of recency
- `maxCacheSize#` = defines how many entries wie keep in `cacheEntries`
- `.initialize§` =
- wires up the external references
- recovers `maxCacheSize#` from the configuration
- recovers `addressABIMap°` from the `state°`
- recovers `cacheEntries[` from the `addressABIMap°`
- ensures `addressABIMap°` and `cacheEntries[` comply with `maxCacheSize#`
- `touchCache§` `address"` =
- unshifts the most recently used cache entry to the front of the list
- forgets the latest entries which are too much
- `.getABI§` `address"` =
if contract is available in the cache then return `addessABIMap[address]`
otherwise retrieve the abi from the ABI Cache Service
`touchCache(address)`
`return addressABIMap[address]`