1 files changed, 146 insertions, 0 deletions
diff --git a/src/oom/oomd-util.h b/src/oom/oomd-util.h
new file mode 100644
index 0000000..f53e4c4
--- /dev/null
+++ b/src/oom/oomd-util.h
@@ -0,0 +1,146 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+#pragma once
+
+#include <stdbool.h>
+
+#include "cgroup-util.h"
+#include "hashmap.h"
+#include "psi-util.h"
+
+#define DUMP_ON_KILL_COUNT 10
+#define GROWING_SIZE_PERCENTILE 80
+
+extern const struct hash_ops oomd_cgroup_ctx_hash_ops;
+
+typedef struct OomdCGroupContext OomdCGroupContext;
+typedef struct OomdSystemContext OomdSystemContext;
+
+typedef int (oomd_compare_t)(OomdCGroupContext * const *, OomdCGroupContext * const *);
+
+struct OomdCGroupContext {
+        char *path;
+
+        ResourcePressure memory_pressure;
+
+        uint64_t current_memory_usage;
+
+        uint64_t memory_min;
+        uint64_t memory_low;
+        uint64_t swap_usage;
+
+        uint64_t last_pgscan;
+        uint64_t pgscan;
+
+        ManagedOOMPreference preference;
+
+        /* These are only used for acting on high memory pressure. */
+        loadavg_t mem_pressure_limit;
+        usec_t mem_pressure_limit_hit_start;
+        usec_t last_had_mem_reclaim;
+};
+
+struct OomdSystemContext {
+        uint64_t mem_total;
+        uint64_t mem_used;
+        uint64_t swap_total;
+        uint64_t swap_used;
+};
+
+OomdCGroupContext *oomd_cgroup_context_free(OomdCGroupContext *ctx);
+DEFINE_TRIVIAL_CLEANUP_FUNC(OomdCGroupContext*, oomd_cgroup_context_free);
+
+/* All hashmaps used with these functions are expected to be of the form
+ * key: cgroup paths -> value: OomdCGroupContext. */
+
+/* Scans all the OomdCGroupContexts in `h` and returns 1 and a set of pointers to those OomdCGroupContexts in `ret`
+ * if any of them have exceeded their supplied memory pressure limits for the `duration` length of time.
+ * `mem_pressure_limit_hit_start` is updated accordingly for the first time the limit is exceeded, and when it returns
+ * below the limit.
+ * Returns 0 and sets `ret` to an empty set if no entries exceeded limits for `duration`.
+ * Returns -ENOMEM for allocation errors. */
+int oomd_pressure_above(Hashmap *h, usec_t duration, Set **ret);
+
+/* Returns true if the amount of memory available (see proc(5)) is below the permyriad of memory specified by `threshold_permyriad`. */
+bool oomd_mem_available_below(const OomdSystemContext *ctx, int threshold_permyriad);
+
+/* Returns true if the amount of swap free is below the permyriad of swap specified by `threshold_permyriad`. */
+bool oomd_swap_free_below(const OomdSystemContext *ctx, int threshold_permyriad);
+
+/* Returns pgscan - last_pgscan, accounting for corner cases. */
+uint64_t oomd_pgscan_rate(const OomdCGroupContext *c);
+
+/* The compare functions will sort from largest to smallest, putting all the contexts with "avoid" at the end
+ * (after the smallest values). */
+static inline int compare_pgscan_rate_and_memory_usage(OomdCGroupContext * const *c1, OomdCGroupContext * const *c2) {
+        uint64_t diff1, diff2;
+        int r;
+
+        assert(c1);
+        assert(c2);
+
+        r = CMP((*c1)->preference, (*c2)->preference);
+        if (r != 0)
+                return r;
+
+        diff1 = oomd_pgscan_rate(*c1);
+        diff2 = oomd_pgscan_rate(*c2);
+        r = CMP(diff2, diff1);
+        if (r != 0)
+                return r;
+
+        return CMP((*c2)->current_memory_usage, (*c1)->current_memory_usage);
+}
+
+static inline int compare_swap_usage(OomdCGroupContext * const *c1, OomdCGroupContext * const *c2) {
+        int r;
+
+        assert(c1);
+        assert(c2);
+
+        r = CMP((*c1)->preference, (*c2)->preference);
+        if (r != 0)
+                return r;
+
+        return CMP((*c2)->swap_usage, (*c1)->swap_usage);
+}
+
+/* Get an array of OomdCGroupContexts from `h`, qsorted from largest to smallest values according to `compare_func`.
+ * If `prefix` is not NULL, only include OomdCGroupContexts whose paths start with prefix. Otherwise all paths are sorted.
+ * Returns the number of sorted items; negative on error. */
+int oomd_sort_cgroup_contexts(Hashmap *h, oomd_compare_t compare_func, const char *prefix, OomdCGroupContext ***ret);
+
+/* If the cgroup is owned by root, or the cgroups represented by `ctx` and
+ * `prefix` are owned by the same user, then set `ctx->preference` using the
+ * `user.oomd_avoid` and `user.oomd_omit` xattrs. Otherwise, set
+ * `ctx->preference` to MANAGED_OOM_PREFERENCE_NONE.
+ *
+ * If `prefix` is NULL or the empty string, it is treated as root. If `prefix`
+ * does not specify an ancestor cgroup of `ctx`, -EINVAL is returned. Returns
+ * negative on all other errors. */
+int oomd_fetch_cgroup_oom_preference(OomdCGroupContext *ctx, const char *prefix);
+
+/* Returns a negative value on error, 0 if no processes were killed, or 1 if processes were killed. */
+int oomd_cgroup_kill(const char *path, bool recurse, bool dry_run);
+
+/* The following oomd_kill_by_* functions return 1 if processes were killed, or negative otherwise. */
+/* If `prefix` is supplied, only cgroups whose paths start with `prefix` are eligible candidates. Otherwise,
+ * everything in `h` is a candidate.
+ * Returns the killed cgroup in ret_selected. */
+int oomd_kill_by_pgscan_rate(Hashmap *h, const char *prefix, bool dry_run, char **ret_selected);
+int oomd_kill_by_swap_usage(Hashmap *h, uint64_t threshold_usage, bool dry_run, char **ret_selected);
+
+int oomd_cgroup_context_acquire(const char *path, OomdCGroupContext **ret);
+int oomd_system_context_acquire(const char *proc_swaps_path, OomdSystemContext *ret);
+
+/* Get the OomdCGroupContext of `path` and insert it into `new_h`. The key for the inserted context will be `path`.
+ *
+ * `old_h` is used to get data used to calculate prior interval information. `old_h` can be NULL in which case there
+ * was no prior data to reference. */
+int oomd_insert_cgroup_context(Hashmap *old_h, Hashmap *new_h, const char *path);
+
+/* Update each OomdCGroupContext in `curr_h` with prior interval information from `old_h`. */
+void oomd_update_cgroup_contexts_between_hashmaps(Hashmap *old_h, Hashmap *curr_h);
+
+void oomd_dump_swap_cgroup_context(const OomdCGroupContext *ctx, FILE *f, const char *prefix);
+void oomd_dump_memory_pressure_cgroup_context(const OomdCGroupContext *ctx, FILE *f, const char *prefix);
+void oomd_dump_system_context(const OomdSystemContext *ctx, FILE *f, const char *prefix);