Add opt-in content spooling to lower retained memory#829
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Add Config::setContentSpooling(): when enabled, each parsed object's decoded stream content is written to a single temporary file (ContentSpool) and read back on demand via PDFObject::getContent(), instead of being held in memory for the document's lifetime. The temp file is removed automatically once the document is destroyed. This lowers the memory retained after parsing and during text extraction; extracted text and document details are byte-for-byte identical with the option on or off (verified across the sample suite). Measured memory retained after parsing (getText output identical), vs master: samples/bugs/PullRequest457.pdf 71 MB -> 30 MB (-58%) samples/DocumentWithLotsOfObjects.pdf 55 MB -> 32 MB (-41%) samples/bugs/Issue356.pdf 25 MB -> 2 MB (-93%) samples/bugs/Issue391.pdf 5 MB -> 2 MB (-62%) Note: on documents whose peak occurs while the raw object graph is being built, spooling alone does not lower the peak - it pairs with incremental object construction, which removes that earlier peak.
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Part 3 of #824
Add Config::setContentSpooling(): when enabled, each parsed object's decoded stream content is written to a single temporary file (ContentSpool) and read back on demand via PDFObject::getContent(), instead of being held in memory for the document's lifetime. The temp file is removed automatically once the document is destroyed.
This lowers the memory retained after parsing and during text extraction; extracted text and document details are byte-for-byte identical with the option on or off (verified across the sample suite).
Measured memory retained after parsing (getText output identical), vs master:
samples/bugs/PullRequest457.pdf 71 MB -> 30 MB (-58%)
samples/DocumentWithLotsOfObjects.pdf 55 MB -> 32 MB (-41%)
samples/bugs/Issue356.pdf 25 MB -> 2 MB (-93%)
samples/bugs/Issue391.pdf 5 MB -> 2 MB (-62%)
Note: on documents whose peak occurs while the raw object graph is being built, spooling alone does not lower the peak - it pairs with incremental object construction (#827), which removes that earlier peak.