ewma: Move private struct into header private section

Facilitate testing.

Part of #32196.

Signed-off-by: David Goulet <dgoulet@torproject.org>

1 files changed, 106 insertions, 1 deletions

diff --git a/src/core/or/circuitmux_ewma.h b/src/core/or/circuitmux_ewma.h
index b45ce1f916..dcfbc17a82 100644
--- a/src/core/or/circuitmux_ewma.h
+++ b/src/core/or/circuitmux_ewma.h
@@ -22,9 +22,114 @@ void cmux_ewma_set_options(const or_options_t *options,
 void circuitmux_ewma_free_all(void);
 
 #ifdef CIRCUITMUX_EWMA_PRIVATE
+
+/*** EWMA structures ***/
+
+typedef struct cell_ewma_s cell_ewma_t;
+typedef struct ewma_policy_data_s ewma_policy_data_t;
+typedef struct ewma_policy_circ_data_s ewma_policy_circ_data_t;
+
+/**
+ * The cell_ewma_t structure keeps track of how many cells a circuit has
+ * transferred recently.  It keeps an EWMA (exponentially weighted moving
+ * average) of the number of cells flushed from the circuit queue onto a
+ * connection in channel_flush_from_first_active_circuit().
+ */
+
+struct cell_ewma_s {
+  /** The last 'tick' at which we recalibrated cell_count.
+   *
+   * A cell sent at exactly the start of this tick has weight 1.0. Cells sent
+   * since the start of this tick have weight greater than 1.0; ones sent
+   * earlier have less weight. */
+  unsigned int last_adjusted_tick;
+  /** The EWMA of the cell count. */
+  double cell_count;
+  /** True iff this is the cell count for a circuit's previous
+   * channel. */
+  unsigned int is_for_p_chan : 1;
+  /** The position of the circuit within the OR connection's priority
+   * queue. */
+  int heap_index;
+};
+
+struct ewma_policy_data_s {
+  circuitmux_policy_data_t base_;
+
+  /**
+   * Priority queue of cell_ewma_t for circuits with queued cells waiting
+   * for room to free up on the channel that owns this circuitmux.  Kept
+   * in heap order according to EWMA.  This was formerly in channel_t, and
+   * in or_connection_t before that.
+   */
+  smartlist_t *active_circuit_pqueue;
+
+  /**
+   * The tick on which the cell_ewma_ts in active_circuit_pqueue last had
+   * their ewma values rescaled.  This was formerly in channel_t, and in
+   * or_connection_t before that.
+   */
+  unsigned int active_circuit_pqueue_last_recalibrated;
+};
+
+struct ewma_policy_circ_data_s {
+  circuitmux_policy_circ_data_t base_;
+
+  /**
+   * The EWMA count for the number of cells flushed from this circuit
+   * onto this circuitmux.  Used to determine which circuit to flush
+   * from next.  This was formerly in circuit_t and or_circuit_t.
+   */
+  cell_ewma_t cell_ewma;
+
+  /**
+   * Pointer back to the circuit_t this is for; since we're separating
+   * out circuit selection policy like this, we can't attach cell_ewma_t
+   * to the circuit_t any more, so we can't use SUBTYPE_P directly to a
+   * circuit_t like before; instead get it here.
+   */
+  circuit_t *circ;
+};
+
+#define EWMA_POL_DATA_MAGIC 0x2fd8b16aU
+#define EWMA_POL_CIRC_DATA_MAGIC 0x761e7747U
+
+/*** Downcasts for the above types ***/
+
+/**
+ * Downcast a circuitmux_policy_data_t to an ewma_policy_data_t and assert
+ * if the cast is impossible.
+ */
+
+static inline ewma_policy_data_t *
+TO_EWMA_POL_DATA(circuitmux_policy_data_t *pol)
+{
+  if (!pol) return NULL;
+  else {
+    tor_assert(pol->magic == EWMA_POL_DATA_MAGIC);
+    return DOWNCAST(ewma_policy_data_t, pol);
+  }
+}
+
+/**
+ * Downcast a circuitmux_policy_circ_data_t to an ewma_policy_circ_data_t
+ * and assert if the cast is impossible.
+ */
+
+static inline ewma_policy_circ_data_t *
+TO_EWMA_POL_CIRC_DATA(circuitmux_policy_circ_data_t *pol)
+{
+  if (!pol) return NULL;
+  else {
+    tor_assert(pol->magic == EWMA_POL_CIRC_DATA_MAGIC);
+    return DOWNCAST(ewma_policy_circ_data_t, pol);
+  }
+}
+
 STATIC unsigned cell_ewma_get_current_tick_and_fraction(double *remainder_out);
 STATIC void cell_ewma_initialize_ticks(void);
-#endif
+
+#endif /* CIRCUITMUX_EWMA_PRIVATE */
 
 #endif /* !defined(TOR_CIRCUITMUX_EWMA_H) */