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take() method added for single-read values #160

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Merged
erdii merged 3 commits into from
Dec 4, 2019
Merged

take() method added for single-read values #160

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7c3be0d
feat(take): Added take() method for single-use values
KrishnaPG Nov 27, 2019
5248736
chore: reverting to master version
KrishnaPG Nov 27, 2019
640fa54
fix(take): fixes the falsy values bug
KrishnaPG Dec 4, 2019
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20 changes: 20 additions & 0 deletions _src/lib/node_cache.coffee
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Original file line number Diff line number Diff line change
Expand Up @@ -287,6 +287,26 @@ module.exports = class NodeCache extends EventEmitter

return delCount

# ## take
#
# get the cached value and remove the key from the cache.
# Equivalent to calling `get(key)` + `del(key)`.
# Useful for implementing `single use` mechanism such as OTP, where once a value is read it will become obsolete.
#
# **Parameters:**
#
# * `key` ( String | Number ): cache key
#
# **Example:**
#
# myCache.take "myKey", ( err, val )
#
take: ( key )=>
_ret = @get(key)
if (_ret?)
@del(key)
return _ret

# ## ttl
#
# reset or redefine the ttl of a key. `ttl` = 0 means infinite lifetime.
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61 changes: 61 additions & 0 deletions _src/test/mocha_test.coffee
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Expand Up @@ -70,6 +70,7 @@ describe "`#{pkg.name}@#{pkg.version}` on `node@#{process.version}`", () ->
b:
x: 2
y: 3
otp: randomString 10
return

it "set key", () ->
Expand Down Expand Up @@ -103,6 +104,66 @@ describe "`#{pkg.name}@#{pkg.version}` on `node@#{process.version}`", () ->
0.should.eql count
return

it "take key", () ->
# make sure we are starting fresh
res = localCache.has("otp")
res.should.eql false

# taking a non-exitent value should be fine
res = localCache.take("otp")
should.not.exist(res)

# check if otp insertion suceeded
res = localCache.set "otp", state.otp, 0
true.should.eql res

# are we able to check the presence of the key?
res = localCache.has("otp")
res.should.eql true

# not once, but twice?
# This proves that keys can be accessed as many times as required, but
# not the value. The `take()` method makes the values as single-read, not the keys.
res = localCache.has("otp")
res.should.eql true

# take the value
otp = localCache.take("otp")
otp.should.eql state.otp

# key should not be present anymore once the value is read
res = localCache.has("otp")
res.should.eql false

# and, re-insertions are not probhitied
res = localCache.set "otp", "some other value"
true.should.eql res

# should be able take the value again
otp = localCache.take("otp")
otp.should.eql "some other value"

# key should not be present anymore, again
res = localCache.has("otp")
res.should.eql false
return

it "take key with falsy values", () ->
# make sure we are starting fresh
res = localCache.has("otp")
res.should.eql false

# insert a falsy value and take it
res = localCache.set "otp", 0
true.should.eql res
otp = localCache.take("otp")
otp.should.eql 0

# key should not exist anymore
res = localCache.has("otp")
res.should.eql false
return

it "update key (and get it to check if the update worked)", () ->
res = localCache.set state.key, state.value2, 0
true.should.eql res
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