Allow receivers/processors to know when the queue is full (#10070)

Marked as experimental as it is the Queue.

---------

Signed-off-by: Bogdan Drutu <bogdandrutu@gmail.com>
Co-authored-by: Dmitrii Anoshin <anoshindx@gmail.com>
Co-authored-by: Yang Song <songy23@users.noreply.github.com>

.chloggen/expose-err-queue-full.yaml

@@ -0,0 +1,20 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the component, or a single word describing the area of concern, (e.g. otlpreceiver)
+component: exporterqueue
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Expose ErrQueueIsFull so upstream components can retry or apply backpressure.
+
+# One or more tracking issues or pull requests related to the change
+issues: [10070]
+
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: [api]

exporter/exporterqueue/queue.go

@@ -11,6 +11,11 @@ import (
 	"go.opentelemetry.io/collector/exporter/internal/queue"
 )
 
+// ErrQueueIsFull is the error that Queue returns when full.
+// Experimental: This API is at the early stage of development and may change without backward compatibility
+// until https://github.com/open-telemetry/opentelemetry-collector/issues/8122 is resolved.
+var ErrQueueIsFull = queue.ErrQueueIsFull
+
 // Queue defines a producer-consumer exchange which can be backed by e.g. the memory-based ring buffer queue
 // (boundedMemoryQueue) or via a disk-based queue (persistentQueue)
 // Experimental: This API is at the early stage of development and may change without backward compatibility