ex_shards v0.2.0 ExShards.Local
Local Shards API – This is the equivalent module to shards_local.
Examples
# create a table with default options
iex> ExShards.Local.new :mytab
:mytab
iex> ExShards.Local.insert :mytab, [k1: 1, k2: 2, k3: 3]
true
iex> for k <- [:k1, :k2, :k3] do
[{_, v}] = ExShards.Local.lookup(:mytab, k)
v
end
[1, 2, 3]
iex> ExShards.Local.delete :mytab, :k3
true
iex> ExShards.Local.lookup :mytab, :k3
[]
# let's create another table
iex> ExShards.Local.new :mytab2, [{:n_shards, 4}]
:mytab2Links:
- shards_local
- API Reference
ExShards.Ext– Extended API
Summary
Functions
Drops the given keys from tab
Fetches the value for a specific key in the given tab
Fetches the value for a specific key in the given tab, erroring out if
tab doesn’t contain key
Gets the value or a list of values for a specific key in tab
Gets the value from key and updates it, all in one pass
Gets the value from key and updates it. Raises if there is no key
Returns whether the given key exists in the given tab
Returns all keys from tab
Returns and removes the value(s) associated with key in tab
Puts the given value under key in tab
Puts the given value under key unless the entry key
already exists in tab
Removes the entry in tab for a specific key
This function is analogous to :shards.insert/2,3, but it returns
the table name instead of true
Drops the given keys from tab and returns a map with all dropped
key-value pairs
Updates the key in tab with the given function
Updates key with the given function
This function is analogous to :shards.update_element/3,4, but it returns
the table name instead of true
Returns all values from tab
Functions
Drops the given keys from tab.
If keys contains keys that are not in tab, they’re simply ignored.
Examples
iex> ExShards.set(:mytab, a: 1, b: 2, a: 3, c: 4)
iex> ExShards.drop(:mytab, [:a, :b, :e])
:mytab
iex> ExShards.keys(:mytab)
[:c]Callback implementation for ExShards.Ext.drop/3.
Fetches the value for a specific key in the given tab.
If tab contains the given key with value value, then {:ok, value}
is returned. If tab doesn’t contain key, :error is returned.
Keep in mind that only one result is returned always, in case of :bag
or :duplicate bag, only the first match is returned.
Examples
iex> ExShards.fetch(:mytab, :a)
{:ok, 1}
iex> ExShards.fetch(:mytab, :b)
:errorCallback implementation for ExShards.Ext.fetch/3.
Fetches the value for a specific key in the given tab, erroring out if
tab doesn’t contain key.
If tab contains the given key, the corresponding value is returned. If
tab doesn’t contain key, a KeyError exception is raised.
Keep in mind that only one result is returned always, in case of :bag
or :duplicate bag, only the first match is returned.
Examples
iex> ExShards.fetch!(:mytab, :a)
1
iex> ExShards.fetch!(:mytab, :b)
** (KeyError) key :b not found in: :mytabCallback implementation for ExShards.Ext.fetch!/3.
Gets the value or a list of values for a specific key in tab.
Return possibilities:
value– Ifkeyis present intabwith valuevalue(only one element matches).[value]– In case of multiple elements matches with the keykey. This behaviour is expected when the table is either a:bagor a:duplicate_bag.default– Ifkeyis not present intab(defaultisnilunless specified otherwise).
Examples
iex> ExShards.get(:mytab, :a)
nil
iex> :mytab |> ExShards.put(:a, 1) |> ExShards.get(:a)
1
iex> ExShards.get(:mytab, :b)
nil
iex> ExShards.get(:mytab, :b, 3)
3
iex> :mytab |> ExShards.set(c: 2, c: 3) |> ExShards.get(:c)
[2, 3]Callback implementation for ExShards.Ext.get/4.
Gets the value from key and updates it, all in one pass.
fun is called with the current value under key in tab (or nil
if key is not present in tab) and must return a two-element tuple:
the “get” value (the retrieved value, which can be operated on before
being returned) and the new value to be stored under key. fun may
also return :pop, which means the current value shall be removed
from tab and returned (making this function behave like
pop(tab, key).
The returned value is a tuple with the “get” value returned by
fun and a new map with the updated value under key.
Examples
iex> :mytab |> ExShards.put(:a, 1) |> ExShards.get(:a)
1
iex> ExShards.get_and_update(:mytab, :a, fn current_value ->
...> {current_value, "new value!"}
...> end)
{1, "new value!"}
iex> ExShards.get_and_update(:mytab, :b, fn current_value ->
...> {current_value, "new value!"}
...> end)
{nil, "new value!"}
iex> ExShards.get_and_update(:mytab, :a, fn _ -> :pop end)
{"new value!", nil}
iex> ExShards.get_and_update(:mytab, :b, fn _ -> :pop end)
{nil, nil}Callback implementation for ExShards.Ext.get_and_update/4.
Gets the value from key and updates it. Raises if there is no key.
Behaves exactly like get_and_update/3, but raises a KeyError exception if
key is not present in map.
Examples
iex> :mytab |> ExShards.put(:a, 1) |> ExShards.get(:a)
1
iex> ExShards.get_and_update(:mytab, :a, fn current_value ->
...> {current_value, "new value!"}
...> end)
{1, "new value!"}
iex> ExShards.get_and_update(:mytab, :b, fn current_value ->
...> {current_value, "new value!"}
...> end)
** (KeyError) key :b not found in: :mytab
iex> ExShards.get_and_update(:mytab, :a, fn _ -> :pop end)
{"new value!", nil}Callback implementation for ExShards.Ext.get_and_update!/4.
Returns whether the given key exists in the given tab.
Examples
iex> ExShards.has_key?(:mytab, :a)
true
iex> ExShards.has_key?(:mytab, :b)
falseCallback implementation for ExShards.Ext.has_key?/3.
Returns all keys from tab.
Examples
iex> ExShards.set(:mytab, a: 1, b: 2, c: 3)
:mytab
iex> ExShards.keys(:mytab)
[:a, :b, :c]WARNING: This is an expensive operation, try DO NOT USE IT IN PROD.
Callback implementation for ExShards.Ext.keys/2.
Returns and removes the value(s) associated with key in tab.
Return possibilities:
{tab, value}– Ifkeyis present intabwith valuevalue.{tab, [value]}– In case of multiple matches with the keykey. This behaviour is expected when the table is either a:bagor a:duplicate_bag.{tab, default}– Ifkeyis not present intab.
Examples
iex> :mytab |> ExShards.set(a: 1, b: 2, a: 2) |> ExShards.pop(:a)
[1, 2]
iex> ExShards.pop(:mytab, :b)
2
iex> ExShards.pop(:mytab, :c)
nil
iex> ExShards.pop(:mytab, :c, 3)
3Callback implementation for ExShards.Ext.pop/4.
Puts the given value under key in tab.
Examples
iex> :mytab |> ExShards.put(:a, 1) |> ExShards.fetch!(:a)
1
iex> :mytab |> ExShards.put(:a, 3) |> ExShards.fetch!(:a)
3Callback implementation for ExShards.Ext.put/4.
Puts the given value under key unless the entry key
already exists in tab.
Examples
iex> ExShards.put_new(:mytab, :a, 1) |> ExShards.fetch!(:a)
1
iex> ExShards.put_new(:mytab, :a, 3) |> ExShards.fetch!(:a)
1Callback implementation for ExShards.Ext.put_new/4.
Removes the entry in tab for a specific key.
If the key does not exist, returns tab unchanged.
Examples
iex> :mytab |> ExShards.put(:a, 1) |> ExShards.fetch!(:a)
1
iex> ExShards.delete(:mytab, :a) |> ExShards.get(:a)
nil
iex> ExShards.delete(:mytab, :b) |> ExShards.get(:b)
nilCallback implementation for ExShards.Ext.remove/3.
This function is analogous to :shards.insert/2,3, but it returns
the table name instead of true.
Examples
iex> :mytab |> ExShards.set(a:1, b: 2) |> ExShards.get(:a)
1
iex> :mytab |> ExShards.set(b: 3) |> ExShards.get(:b)
3Callback implementation for ExShards.Ext.set/3.
Drops the given keys from tab and returns a map with all dropped
key-value pairs.
If keys contains keys that are not in tab, they’re simply ignored.
Examples
iex> ExShards.set(:mytab, a: 1, b: 2, a: 3, c: 4)
iex> ExShards.take_and_drop(:mytab, [:a, :b, :e])
%{a: [1, 3], b: 2}
iex> ExShards.get(:mytab, :a)
nilCallback implementation for ExShards.Ext.take_and_drop/3.
Updates the key in tab with the given function.
If key is present in tab with value value, fun is invoked with
argument value and its result is used as the new value of key.
If key is not present in tab, initial is inserted as the value
of key.
This functions only works for :set or :ordered_set tables.
Examples
iex> :mytab |> ExShards.put(:a, 1) |> ExShards.update(:a, 13, &(&1 * 2)) |> ExShards.get(:a)
2
iex> :mytab |> ExShards.update(:b, 11, &(&1 * 2)) |> ExShards.get(:b)
11Callback implementation for ExShards.Ext.update/5.
Updates key with the given function.
If key is present in tab with value value, fun is invoked with
argument value and its result is used as the new value of key.
If key is not present in tab, a KeyError exception is raised.
This functions only works for :set or :ordered_set tables.
Examples
iex> :mytab |> ExShards.put(:a, 1) |> ExShards.update!(:a, &(&1 * 2)) |> ExShards.get(:a)
2
iex> :mytab |> ExShards.update(:b, &(&1 * 2))
** (KeyError) key :b not found in: :mytabCallback implementation for ExShards.Ext.update!/4.
This function is analogous to :shards.update_element/3,4, but it returns
the table name instead of true.
This functions only works for :set or :ordered_set tables.
Examples
iex> :mytab |> ExShards.put(:a, 1) |> ExShards.update_elem(:a, {2, 11}) |> ExShards.get(:a)
11
iex> :mytab |> ExShards.update_elem(:b, {2, 22}) |> ExShards.get(:b)
nilCallback implementation for ExShards.Ext.update_elem/4.
Returns all values from tab.
Examples
iex> ExShards.set(:mytab, a: 1, b: 2, c: 3)
:mytab
iex> ExShards.values(:mytab)
[:a, :b, :c]WARNING: This is an expensive operation, try DO NOT USE IT IN PROD.
Callback implementation for ExShards.Ext.values/2.