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https://github.com/felt/tippecanoe.git
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Erica FischerandCursor
4f4214ee23
Forking and waitpid()-ing for the -C/-c shell filters used to happen directly in the multi-threaded tiling threads, which made fork() expensive (full COW of the parent's address space) and unsafe (other threads could hold libc/malloc locks at fork time). Now we pre-fork a small pool of single-threaded worker processes once, before any tiling or reader threads are spawned, and the tiling threads ask a worker to fork+exec the shell child on their behalf, receiving the input/output pipe fds back via SCM_RIGHTS. The fork() and waitpid() happen entirely inside the single-threaded worker, where they are cheap and only block that worker. Co-authored-by: Cursor <cursoragent@cursor.com>
18 lines
1.1 KiB
C++
18 lines
1.1 KiB
C++
struct key_pool;
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// Identifies which worker process is currently running a filter on this
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// thread's behalf. Returned by setup_filter and consumed by wait_filter.
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struct filter_handle {
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ssize_t worker_idx = -1;
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};
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std::vector<mvt_layer> filter_layers(const char *filter, std::vector<mvt_layer> &layer, unsigned z, unsigned x, unsigned y, std::vector<std::map<std::string, layermap_entry>> *layermaps, size_t tiling_seg, std::vector<std::vector<std::string>> *layer_unmaps, int extent);
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void setup_filter(const char *filter, int *write_to, int *read_from, filter_handle *handle, unsigned z, unsigned x, unsigned y);
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void wait_filter(filter_handle handle);
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serial_feature parse_feature(json_pull *jp, int z, unsigned x, unsigned y, std::vector<std::map<std::string, layermap_entry>> *layermaps, size_t tiling_seg, std::vector<std::vector<std::string>> *layer_unmaps, bool filters, key_pool &key_pool);
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// Pre-fork the pool of single-threaded filter worker processes used by
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// setup_filter / wait_filter. Must be called from a single-threaded context
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// (i.e. before any reader or tiling threads are spawned).
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void filter_workers_init(size_t n);
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