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Atomic Caching

Source: R/cache.R
cache.Rd

Functions for caching results attached to atomic objects

Usage

newcache(x)

jamcache(x)

cache(x)

setcache(x, which, value)

getcache(x, which)

remcache(x)

# S3 method for class 'cache'
print(x, all.names = FALSE, pattern, ...)

Arguments

x

an integer64 vector (or a cache object in case of print.cache)

which

A character naming the object to be retrieved from the cache or to be stored in the cache

value

An object to be stored in the cache

all.names, pattern

passed to ls() when listing the cache content

...

ignored

Value

See details

Details

A cache is an environment attached to an atomic object with the attribute name 'cache'. It contains at least a reference to the atomic object that carries the cache. This is used when accessing the cache to detect whether the object carrying the cache has been modified meanwhile.

Functions

  • newcache(): creates a new cache referencing x

  • jamcache(): forces x to have a cache

  • cache(): returns the cache attached to x if it is not found to be outdated

  • setcache(): assigns a value into the cache of x

  • getcache(): gets cache value 'which' from x

  • remcache(): removes the cache from x

See also

bit::still.identical() for testing whether to symbols point to the same RAM.

Functions that get and set small cache-content automatically when a cache is present: bit::na.count(), bit::nvalid(), bit::is.sorted(), bit::nunique() and bit::nties()

Setting big caches with a relevant memory footprint requires a conscious decision of the user: hashcache, sortcache, ordercache, sortordercache

Functions that use big caches: match.integer64(), %in%.integer64, duplicated.integer64(), unique.integer64(), unipos(), table.integer64(), keypos(), tiepos(), rank.integer64(), prank(), qtile(), quantile.integer64(), median.integer64(), and summary.integer64()

Examples

  x <- as.integer64(sample(c(rep(NA, 9), 1:9), 32, TRUE))
  y <- x
  still.identical(x,y)
#> [1] TRUE
  y[1] <- NA
  still.identical(x,y)
#> [1] FALSE
  mycache <- newcache(x)
  ls(mycache)
#> [1] "x"
  mycache
#> cache_integer64: x
  rm(mycache)
  jamcache(x)
#> cache_integer64: x
  cache(x)
#> cache_integer64: x
  x[1] <- NA
  cache(x)
#> Warning: removed outdated cache
#> NULL
  getcache(x, "abc")
#> NULL
  setcache(x, "abc", 1)
#> cache_integer64: abc - x
  getcache(x, "abc")
#> [1] 1
  remcache(x)
  cache(x)
#> NULL