Class CachingPriceFeed

java.lang.Object

com.codename1.crypto.market.CachingPriceFeed

All Implemented Interfaces:

PriceFeed

public class CachingPriceFeed
extends Object
implements PriceFeed

A PriceFeed that remembers each pair's answer for a while. A wallet screen that refreshes every few seconds then asks the source once per pair per interval, which is what keeps it inside a public API's rate limit. When the source fails and a remembered answer is no older than the stale limit, that answer is returned rather than the failure.

The cache keeps at most 512 pairs and is not synchronized; on the backend give each thread its own or guard it.

Constructor Summary

Constructors

Constructor	Description
CachingPriceFeed(PriceFeed source, long freshMillis, long staleMillis)	A cache answering from memory for freshMillis, and on a source failure for up to staleMillis.

Method Summary

Modifier and Type	Method	Description
void	clear()	Forgets every remembered answer.
Quote	getQuote(String base, String quote)	The price of base in quote, by ticker (BTC, ETH, USD, EUR); case does not matter.
protected long	now()	The clock, in milliseconds; a test overrides it.

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

CachingPriceFeed

public CachingPriceFeed(PriceFeed source,
 long freshMillis,
 long staleMillis)

A cache answering from memory for freshMillis, and on a source failure for up to staleMillis.

Method Details

getQuote

public Quote getQuote(String base,
 String quote)
               throws IOException

Description copied from interface: PriceFeed

The price of base in quote, by ticker (BTC, ETH, USD, EUR); case does not matter.

Throws

• IOException: when the source cannot be reached or does not know the pair

Specified by:

getQuote in interface PriceFeed

Throws:

IOException

clear

public void clear()

Forgets every remembered answer.

now

protected long now()

The clock, in milliseconds; a test overrides it.