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static void procstat_get_monitored_pids(zbx_vector_uint64_t *pids, const zbx_vector_ptr_t *queries, int pids_num)/*** Copyright (C) 2001-2025 Zabbix SIA**** This program is free software: you can redistribute it and/or modify it under the terms of** the GNU Affero General Public License as published by the Free Software Foundation, version 3.**** This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;** without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.** See the GNU Affero General Public License for more details.**** You should have received a copy of the GNU Affero General Public License along with this program.** If not, see <https://www.gnu.org/licenses/>.**//* * The process CPU statistics are stored using the following memory layout. * * .--------------------------------------. * | header | * | ------------------------------------ | * | process cpu utilization queries | * | and historical data | * | ------------------------------------ | * | free space | * '--------------------------------------' * * Because the shared memory can be resized by other processes instead of * using pointers (when allocating strings, building single linked lists) * the memory offsets from the beginning of shared memory segment are used. * 0 offset is interpreted similarly to NULL pointer. * * Currently integer values are used to store offsets to internally allocated * memory which leads to 2GB total size limit. * * During every data collection cycle collector does the following: * 1) acquires list of all processes running on system * 2) builds a list of processes monitored by queries * 3) reads total cpu utilization snapshot for the monitored processes * 4) calculates cpu utilization difference by comparing with previous snapshot * 5) updates cpu utilization values for queries. * 6) saves the last cpu utilization snapshot * * Initialisation. * * zbx_procstat_init() initialises procstat dshm structure but doesn't allocate memory from the system * (zbx_dshm_create() called with size 0). * * the first call of procstat_add() allocates the shared memory for the header and the first query * via call to zbx_dshm_realloc(). * * The header is initialised in procstat_copy_data() which is called back from zbx_dshm_realloc(). * * Memory allocation within dshm. * * Ensure that memory segment has enough free space with procstat_dshm_has_enough_space() before * allocating space within segment with procstat_alloc() or functions that use it. * * Check how much of the allocated dshm is actually used by procstat by procstat_dshm_used_size(). * * Change the dshm size with zbx_dshm_realloc(). * * Synchronisation. * * agentd processes share a single instance of ZBX_COLLECTOR_DATA (*collector) containing reference * to shared procstat memory segment. * * Each agentd process also holds local reference to procstat shared memory segment. * * The system keeps the shared memory segment until the last process detaches from it. * * Synchronise both references with procstat_reattach() before using procstat shared memory segment. *//* local reference to the procstat shared memory */static zbx_dshm_ref_t procstat_ref;typedef struct{ /* a linked list of active queries (offset of the first active query) */ int queries; /* the total size of the allocated queries and strings */ int size_allocated; /* the total shared memory segment size */ size_t size;}zbx_procstat_header_t;