Add isfull for buffered Channels

base/channels.jl

@@ -538,6 +538,37 @@ true
 """
 isready(c::Channel) = n_avail(c) > 0
 isempty(c::Channel) = n_avail(c) == 0
+
+"""
+    isfull(c::Channel)
+
+Determines whether a buffered [`Channel`](@ref) is full. Unbuffered channels are never full.
+Returns immediately, does not block.
+
+# Examples
+
+Buffered channel:
+```jldoctest
+julia> c = Channel(1);
+
+julia> isfull(c)
+false
+
+julia> put!(c, 1);
+
+julia> isfull(c)
+true
+```
+
+Unbuffered channel:
+```jldoctest
+julia> c = Channel();
+
+julia> isfull(c)
+false
+```
+"""
+isfull(c::Channel) = isbuffered(c) && n_avail(c) >= c.sz_max
 function n_avail(c::Channel)
     # Lock-free equivalent to `length(c.data) + length(c.cond_put.waitq)`
     @atomic :monotonic c.n_avail_items

base/exports.jl

@@ -537,6 +537,7 @@ export
     intersect,
     isdisjoint,
     isempty,
+    isfull,
     issubset,
     issetequal,
     keys,

doc/src/base/parallel.md

@@ -62,6 +62,7 @@ Base.Channel(::Function)
 Base.put!(::Channel, ::Any)
 Base.take!(::Channel)
 Base.isready(::Channel)
+Base.isfull(::Channel)
 Base.fetch(::Channel)
 Base.close(::Channel)
 Base.bind(c::Channel, task::Task)

doc/src/manual/asynchronous-programming.md

@@ -196,6 +196,7 @@ A channel can be visualized as a pipe, i.e., it has a write end and a read end :
     hold up to 64 objects of `MyType` at any time.
   * If a [`Channel`](@ref) is empty, readers (on a [`take!`](@ref) call) will block until data is available.
   * If a [`Channel`](@ref) is full, writers (on a [`put!`](@ref) call) will block until space becomes available.
+  * [`isfull`](@ref) can be used to check if a buffered channel is full.
   * [`isready`](@ref) tests for the presence of any object in the channel, while [`wait`](@ref)
     waits for an object to become available.
   * A [`Channel`](@ref) is in an open state initially. This means that it can be read from and written to