The overall mood is one of sadness and relief. The poem uses the rhythm to convey this mood because by using the different "paces" between the lines, it helps the reader see when the author is feeling melancholy or relieved.
"Though you may hear me holler,
<span>And you may see me cry—
I’ll be dogged, sweet baby,
If you gonna see me die."
By using specific short words and commas, that makes the reader get a sense of the mood - one of sadness and relief at the fact that they are still alive.
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The figurative language used in the above sentence is METAPHOR.
Metaphor is a figure of speech comparing two unrelated objects for rhetorical effects.
The public is compared with swine or pig.
Advertising is compared with the rattling of a stick inside a swill-bucket.