upgrade_all()

Description

Compatibility

Present in every tracked release (6.7.7 to 7.1.0), and compiles on PHP 7.4 through 8.6-dev.

Performance profile

How much work a call to upgrade_all() does, and what it touches: the algorithmic scaling, the Zend instruction count per call across PHP versions, the hooks it hands control to, and the core code that calls it. Measured from the compiled opcodes, not a stopwatch, so every number is identical on any machine running the same PHP version, and every function in core is ranked by cost.

Cost class

Moderate

Reads stored settings via update_option(), cached per request but not free on a cold cache.

Scaling

Constant

No loop in the body: the same number of instructions runs whatever you pass in.

Instructions

102–124

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 193.

Plugin surface

None

Nothing here hands control to plugin code.

Called by

1

1 place in core call this, so the cost is paid more often than your own code shows.

What it touches

• optionoption read or writeupdate_option()called directly
• serializeserialisationmaybe_unserialize()one call below upgrade_all()
• hookthird-party callbacksdo_action()one call below upgrade_all()
• transienttransientdelete_transient()one call below upgrade_all()
• cacheobject cachewp_cache_get()one call below upgrade_all()

Further down the call graph this can also reach query. That is the worst case, several calls deep and usually down an error path, not what a normal call pays.

What one call costs · 4000 distinct outcomes

One number would be a lie: the work depends on which branch runs. These are every distinct cost upgrade_all() can have, taken from its control-flow graph on PHP 8.5.