What constitutes "good cause" for delay in a criminal trial?

Although section 1382 prohibits delay without "good cause" it does not define good cause. Instead "[w]hat constitutes good cause for the delay of a criminal trial is a matter that lies within the discretion of the trial court." (People v. Johnson, supra, 26 Cal.3d 557, 570, 162 Cal.Rptr. 431, 606 P.2d 738.) The circumstances that may constitute good cause and the amount of delay those circumstances may justify are varied.